2β-substituted-6-alkylidene penicillanic acid derivatives as β-lactamase inhibitors

ABSTRACT

Compounds of formula I: ##STR1## wherein R 1 , R 2 , R 3 , R 4  and n have any of the values defined in the specification, and their pharmaceutically acceptable salts, are useful for inhibiting β-lactamase enzymes, for enhancing the activity of β-lactam antibiotics, and for treating β-lactam resistant bacterial infections in a mammal. The invention also provides pharmaceutical compositions, processes for preparing compounds of formula I, and novel intermediates useful for the synthesis of compounds of formula I.

PRIORITY OF INVENTION

This application claims priority of invention under 35 U.S.C. §119(e)from U.S. Provisional Application Number 60/070,240, filed Dec. 29,1997.

BACKGROUND OF THE INVENTION

The most important mechanism of microbial resistance to β-lactamantibiotics is the bacterial production of β-lactamases, enzymes whichhydrolytically destroy β-lactam antibiotics, such as penicillins andcephalosporins. This type of resistance can be transferred horizontallyby plasmids that are capable of rapidly spreading the resistance, notonly to other members of the same strain, but even to other species. Dueto such rapid gene transfer, a patient can become infected withdifferent organisms, each possessing the same β-lactamase.

β-lactamase enzymes have been organized into four molecular classes: A,B, C and D based on amino acid sequence. Class A, includes RTEM and theβ-lactamase of Staphylococcus aureus, class C, includes the lactamasederived from P99 Enterobacter cloacae, and class D are serinehydrolases. Class A enzymes have a molecular weight of about 29 kDa andpreferentially hydrolyze penicillins. The class B lactamases aremetalloenzymes and have a broader substrate profile than the proteins inthe other classes. Class C enzymes include the chromosomalcephalosporinases of gram-negative bacteria and have molecular weightsof approximately 39 kDa. The recently recognized class D enzymes exhibita unique substrate profile that differs significantly from the profileof both class A and class C enzymes.

The class C cephalosporinases, in particular, are responsible for theresistance of gram-negative bacteria to a variety of both traditionaland newly designed antibiotics. The Enterobacter species, whichpossesses a class C enzyme, is now the third greatest cause ofnosocomial infections in the United States. This class of enzymes oftenhas poor affinities for inhibitors of the class A enzymes, such asclavulanic acid, a commonly prescribed inhibitor, and to common in vitroinactivators, such as 6-β-iodopenicillanate.

One strategy for overcoming this rapidly evolving bacterial resistanceis the synthesis and administration of β-lactamase inhibitors.Frequently, β-lactamase inhibitors do not possess antibiotic activitythemselves and are thus administered together with an antibiotic. Oneexample of such a synergistic mixture is "AUGMENTIN" (a registeredtrademark of Smithkline Beecham Inc), which contains the antibioticamoxicillin and the β-lactamase inhibitor, clavulanic acid.

Thus, there is a continuing need for novel β-lactamase inhibitors.

SUMMARY OF THE INVENTION

The present invention provides novel penicillin derivatives that arepotent inhibitors of β-lactamase enzymes. Accordingly, the inventionprovides a compound of formula (I): ##STR2## wherein R¹ and R² are eachindependently hydrogen, (C₁ -C₁₀)alkyl, (C₃ -C₈)cycloalkyl, (C₂-C₁₀)alkenyl, (C₂ -C₁₀)alkynyl, --COOR_(a), --CONR_(b) R_(c), cyano,--C(═O)R_(d), --OR_(e), aryl, heteroaryl, oxazolidinyl, isoxazolidinyl,morpholinyl, --S(O)_(m) R_(f), --NR_(g) R_(h), azido, or halo;

R³ is (C₃ -C₁₀)alkyl, (C₂ -C₁₀)alkenyl, (C₂ -C₁₀)alkynyl, (C₁-C₁₀)alkanoyl, (C₃ -C₈)cycloalkyl, aryl, heteroaryl, aryl(C₁ -C₁₀)alkyl,heteroaryl(C₁ -C₁₀)alkyl, or --CH₂ R_(i), wherein R_(i) is halo, cyano,cyanato, --OR_(j), --NR_(k) R_(i), azido, --SR_(m), or (C₃-C₈)cycloalkyl;

R⁴ is hydrogen, (C₁ -C₁₀)alkyl, (C₃ -C₈)cycloalkyl, (C₂ -C₁₀)alkenyl,(C₂ -C₁₀)alkynyl, aryl, or heteroaryl;

m and n are each independently 0, 1, or 2;

each R_(a) -R_(f) is independently hydrogen, (C₁ -C₁₀)alkyl, (C₃-C₈)cycloalkyl, (C₂ -C₁₀)alkenyl, (C₂ -C₁₀)alkynyl, aryl, heteroaryl,oxazolidinyl, isoxazolidinyl, or morpholinyl;

each R_(g) or R_(h) is independently hydrogen, (C₁ -C₁₀)alkyl, (C₃-C₈)cycloalkyl, (C₂ -C₁₀)alkenyl, (C₂ -C₁₀)alkynyl, (C₁ -C₁₀)alkanoyl,aryl, benzyl, phenethyl, heteroaryl oxazolidinyl, isoxazolidinyl, ormorpholinyl; or R_(g) and Rh together with the nitrogen to which theyare attached are triazolyl, imidazolyl, oxazolidinyl, isoxazolidinyl,pyrrolyl, morpholino, piperidino, pyrrolidino, pyrazolyl, indolyl, ortetrazolyl;

R_(j) is hydrogen, (C₁ -C₁₀)alkyl, (C₃ -C₈)cycloalkyl, (C₂ -C₁₀)alkenyl,(C₂ -C₁₀)alkynyl, --C(═O)N(R_(p))₂, aryl, heteroaryl, arylcarbonyl,heteroarylcarbonyl, or (C₁ -C₁₀)alkanoyl, wherein each R_(p) isindependently hydrogen, (C₁ -C₁₀)alkyl, aryl, benzyl, phenethyl, orheteroaryl;

each R_(k) or R_(l) is independently hydrogen, (C₁ -C₁₀)alkyl, (C₃-C₈)cycloalkyl, (C₂ -C₁₀)alkenyl, (C₂ -C₁₀) alkynyl, (C₁ -C₁₀)alkanoyl,--C(═O)N(R_(q))₂, aryl, benzyl, phenethyl, heteroaryl oxazolidinyl,isoxazolidinyl, or morpholinyl, wherein each R_(q) is independentlyhydrogen, (C₁ -C₁₀)alkyl, aryl, benzyl, phenethyl, or heteroaryl; orR_(k) and R_(l) together with the nitrogen to which they are attachedare triazolyl, imidazolyl, oxazolidinyl, isoxazolidinyl, pyrrolyl,morpholino, piperidino, pyrrolidino, pyrazolyl, indolyl, or tetrazolyl;and

R_(m) is hydrogen, (C₁ -C₁₀)alkyl, (C₃ -C₈)cycloalkyl, (C₂ -C₁₀)alkenyl,(C₂ -C₁₀)alkynyl, cyano, aryl, benzyl, phenethyl, heteroaryl,oxazolidinyl, isoxazolidinyl, or morpholinyl;

wherein any (C₁ -C₁₀)alkyl, (C₃ -C₈)cycloalkyl, (C₂ -C₁₀)alkenyl, (C₂-C₁₀)alkynyl, (C₁ -C₁₀)alkanoyl, aryl, benzyl, phenethyl, heteroaryl,arylcarbonyl, heteroarylcarbonyl, oxazolidinyl, isoxazolidinyl, ormorpholinyl of R¹ -R⁴, R_(a) -R_(m), or R_(p) -R_(q), may optionally besubstituted with 1, 2, or 3 Z; and each Z is independently halo, nitro,cyano, hydroxy, (C₁ -C₁₀)alkyl, (C₃ -C₈)cycloalkyl, (C₁ -C₁₀)alkoxy, (C₁-C₁₀)alkanoyl, (C₂ -C₁₀)alkanoyloxy, trifluoromethyl, aryl, aryloxy,heteroaryl, or --SR_(n), wherein R_(n) is hydrogen, (C₁ -C₁₀)alkyl, (C₃-C₈)cycloalkyl, aryl, benzyl, phenethyl, or heteroaryl;

and further wherein any aryl, aryloxy, heteroaryl, benzyl, or phenethylof Z may optionally be substituted with 1, 2, or 3 substituents selectedfrom the group consisting of halo, nitro, cyano, hydroxy, (C₁-C₁₀)alkyl, (C₃ -C₈)cycloalkyl, (C₁ -C₁₀)alkoxy, (C₁ -C₁₀)alkanoyl, (C₁-C₁₀)alkanoyloxy, benzyloxy, 4-methoxybenzyloxy, and trifluoromethyl;

or a pharmaceutically acceptable salt thereof.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates the preparation of compounds of the invention.

FIG. 2 illustrates the preparation of compounds of the invention.

FIG. 3 illustrates the preparation of compounds of the invention.

FIG. 4 illustrates the preparation of compounds of the invention.

FIG. 5 illustrates the synthesis of an intermediate of formula (18) thatis useful for preparing compounds of the invention.

FIG. 6 shows the structure of the β-lactamase inhibitors clavulanicacid, tazobactam and the compound of formula 9.

FIG. 7 illustrates the preparation of compounds of the invention (6i,7i, and 8i).

FIG. 8 illustrates the preparation of compounds of the invention (29aand 29b).

DETAILED DESCRIPTION OF THE INVENTION

The following definitions are used, unless otherwise described: halo isfluoro, chloro, bromo, or iodo. Alkyl, alkoxy, alkenyl, alkynyl, etc.denote both straight and branched groups; but reference to an individualradical such as "propyl" embraces only the straight chain radical, abranched chain isomer such as "isopropyl" being specifically referredto. Aryl denotes a phenyl radical or an ortho-fused bicyclic carbocyclicradical having about nine to ten ring atoms in which at least one ringis aromatic. Heteroaryl encompasses a radical attached via a ring carbonof a monocyclic aromatic ring containing five or six ring atomsconsisting of carbon and one to four heteroatoms each selected from thegroup consisting of non-peroxide oxygen, sulfur, and N(X) wherein each Xis absent or is H, O, (C₁ -C₄)alkyl, phenyl or benzyl, as well as aradical of an ortho-fused bicyclic heterocycle of about eight to tenring atoms derived therefrom, particularly a benz-derivative or onederived by fusing a propylene, trimethylene, or tetramethylene diradicalthereto.

It will be appreciated by those skilled in the art that compounds of theinvention having one or more chiral centers may exist and be isolated asoptically active and racemic forms. Some compounds may exhibitpolymorphism. It is to be understood that the present inventionencompasses any racemic, optically-active, polymorphic, orstereoisomeric form, or mixtures thereof, of a compound of theinvention, that possesses the useful properties described herein, itbeing well known in the art how to prepare optically active forms (forexample, by resolution of the racemic form by recrystallizationtechniques, by synthesis, from optically-active starting materials, bychiral synthesis, or by chromatographic separation using a chiralstationary phase) and how to determine β-lactamase inhibitory activityusing the tests described herein, or using other tests which are wellknown in the art. Preferably, the absolute stereochemistry of compoundsof the invention is that shown in formula I.

Specific and preferred values listed below for radicals, substituents,and ranges, are for illustration only and they do not exclude otherdefined values or other values within defined ranges for the radicalsand substituents.

Specifically, (C₁ -C₁₀)alkyl can be methyl, ethyl, propyl, isopropyl,butyl, iso-butyl, sec-butyl, pentyl, 3-pentyl, hexyl, heptyl, octyl,nonyl or decyl; (C₃ -C₈)cycloalkyl can be cyclopropyl, cyclobutyl,cyclopentyl, cyclohexyl, cycloheptyl, or cyclooctyl; (C₁ -C₁₀)alkoxy canbe methoxy, ethoxy, propoxy, isopropoxy, butoxy, iso-butoxy, sec-butoxy,pentoxy, 3-pentoxy, hexyloxy, heptyloxy, octyloxy, nonyloxy, ordecyloxy; (C₂ -C₁₀)alkenyl can be vinyl, allyl, 1-propenyl, 2-propenyl,1-butenyl, 2-butenyl, 3-butenyl, 1,-pentenyl, 2-pentenyl, 3-pentenyl,4-pentenyl, 1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl, 5-hexenyl,1-heptenyl, 2-heptenyl, 3-heptenyl, 4-heptenyl, 5-heptenyl, 6-heptenyl,1-octenyl, 2-octenyl, 3-octenyl, 4-octenyl, 5-octenyl, 6-octenyl,7-octenyl, 1-nonenyl, 2-nonenyl, 3-nonenyl, 4-nonenyl, 5-nonenyl,6-nonenyl, 7-nonenyl, 8-nonenyl, 1-decenyl, 2-decenyl, 3-decenyl,4-decenyl, 5-decenyl, 6-decenyl, 7-decenyl, 8-decenyl, or 9-decenyl; (C₂-C₁₀)alkynyl can be ethynyl, 1-propynyl, 2-propynyl, 1-butynyl,2-butynyl, 3-butynyl, 1-pentynyl, 2-pentynyl, 3-pentynyl, 4-pentynyl,1-hexynyl, 2-hexynyl, 3-hexynyl, 4-hexynyl, 5-hexynyl, 1-heptynyl,2-heptynyl, 3-heptynyl, 4-heptynyl, 5-heptynyl, 6-heptynyl, 1-octynyl,2-octynyl, 3-octynyl, 4-octynyl, 5-octynyl, 6-octynyl, 7-octynyl,1-nonylyl, 2-nonynyl, 3-nonynyl, 4-nonynyl, 5-nonynyl, 6-nonynyl,7-nonynyl, 8-nonynyl, 1-decynyl, 2-decynyl, 3-decynyl, 4-decynyl,5-decynyl, 6-decynyl, 7-decynyl, 8-decynyl, or 9-decynyl; (C₁-C₁₀)alkanoyl can be acetyl, propanoyl, butanoyl, isobutanoyl,pentanoyl, hexanoyl, heptanoyl, octanoyl, nonanoyl, or decanoyl; and (C₂-C₁₀)alkanoyloxy can be acetoxy, propanoyloxy, butanoyloxy,isobutanoyloxy, pentanoyloxy, hexanoyloxy, heptanoyloxy, octanoyloxy,nonanoyloxy, or decanoyloxy. Specifically "aryl" can be phenyl, indenyl,or naphthyl. Specifically, "heteroaryl" can be furyl, imidazolyl,triazolyl, triazinyl, oxazoyl, isoxazoyl, thiazolyl, isothiazoyl,pyrazolyl, pyrrolyl, pyrazinyl, tetrazolyl, pyridyl, (or its N-oxide),thienyl, pyrimidinyl (or its N-oxide), indolyl, isoquinolyl (or itsN-oxide), thiadiazolyl, thiatriazolyl, oxadiazolyl, or quinolyl (or itsN-oxide). More specifically, "heteroaryl" can be furyl, imidazolyl,triazolyl, triazinyl, oxazoyl, isoxazoyl, thiazolyl, isothiazoyl,pyrazolyl, pyrrolyl, pyrazinyl, tetrazolyl, pyridyl, (or its N-oxide),thienyl, pyrimidinyl (or its N-oxide), indolyl, isoquinolyl (or itsN-oxide) or quinolyl (or its N-oxide). More specifically, heteroaryl canbe pyridyl.

Specifically, R_(a) is methyl, ethyl, propyl, isopropyl, butyl,tert-butyl, pentyl, cyclopropyl, cyclopentyl, cyclohexyl, phenyl,toluoyl, anisoyl, mesityl, xylyl, or pyridinyl; R³ is --CH₂ R_(i) ;R_(i) is halo, cyano, cyanato, --OR_(j), --NR_(k) R_(l), azido, or--SR_(m) ; and Z is halo, nitro, cyano, hydroxy, (C₁ -C₁₀)alkoxy, (C₁-C₁₀)alkanoyl, (C₂ -C₁₀)alkanoyloxy, trifluoromethyl or --SR_(n). Morespecifically, R³ is acetoxymethyl, phenylacetoxymethyl,phenoxyacetoxymethyl, chloroacetoxymethyl, pyridylacetoxymethyl,triazolylacetoxymethyl, imidazolylacetoxymethyl,tetrazolylthioacetoxymethyl, or tetrazolylthioacetoxymethyl optionallysubstituted on the tetrazol ring with (C₁ -C₆)alkyl, or aryl.

Another specific value for R³ is acetoxynmethyl, chloroacetoxymethyl,formyloxymethyl, phenylacetoxymethyl,(1-methyl-1H-tetrazol-5-ylthio)acetoxymethyl,(3,4-dihydroxyphenyl)acetoxymethyl,3,4-di(4-methoxybenzyloxy)phenylacetoxymethyl, chloromethyl, formyl, or2-cyanovinyl.

A preferred value for R¹ is hydrogen; for R² is carboxy,tert-butoxycarbonyl, or methoxycarbonyl; for R³ is acetoxymethyl,chloroacetoxymethyl, formyloxymethyl, phenylacetoxymethyl,(1-methyl-1H-tetrazol-5-ylthio)acetoxymethyl,(3,4-dihydroxyphenyl)acetoxymethyl, chloromethyl, formyl, or2-cyanovinyl; for R⁴ is hydrogen or diphenylmethyl; and for n is 2. Amore preferred value for R³ is acetoxymethyl, chloroacetoxymethyl,phenylacetoxymethyl, (3,4-dihydroxyphenyl)acetoxymethyl, or(1-methyl-1H-tetrazol-5-ylthio)acetoxynmethyl.

Another prefered value for R² is pyridyl (e.g. 2-pyridyl).

A preferred group of compounds are compounds of formula I wherein R³ is--CH₂ OR_(j) ; or a pharmaceutically acceptable salt thereof.

Another preferred group of compounds are compounds of formula I whereinR³ is --CH₂ OR_(j) ; and R_(j) is C₂ -alkanoyl, optionally substitutedwith halo, nitro, cyano, hydroxy, (C₃ -C₈)cycloalkyl, (C₁ -C₁₀)alkoxy,(C₁ -C₁₀)alkanoyl, (C₂ -C₁₀)alkanoyloxy, trifluoromethyl, aryl, aryloxy,heteroaryl, or --SR_(n) ; wherein R_(n) is hydrogen, (C₁ -C₁₀)alkyl, (C₃-C₈)cycloalkyl, aryl, benzyl, phenethyl, or heteroaryl; and furtherwherein any aryl, aryloxy, heteroaryl, benzyl, or phenethyl mayoptionally be substituted with 1, 2, or 3 substituents selected from thegroup consisting of halo, nitro, cyano, hydroxy, (C₁ -C₁₀)alkyl, (C₃-C₈)cycloalkyl, (C₁ -C₁₀)alkoxy, (C₁ -C₁₀)alkanoyl, (C₂ -C₁₀)alkanoyloxy, and tri fluoromethyl; or a pharmaceutically acceptablesalt thereof.

A preferred compound is a compound of formula I wherein: R¹ and R² areeach independently hydrogen, (C₁ -C₁₀)alkyl, (C₃ -C₈)cycloalkyl, (C₂-C₁₀)alkenyl, (C₂ -C₁₀)alkynyl, --COOR_(a), --CONR_(b) R_(c), cyano,--C(═O)R_(d), --OR_(e), aryl, heteroaryl, oxazolidinyl, isoxazolidinyl,morpholinyl, --S(O)_(m) R_(f), --NR_(g) R_(h), azido, or halo; R³ is (C₃-C₁₀)alkyl, (C₂ -C₁₀)alkenyl, (C₂ -C₁₀)alkynyl, (C₁ -C₁₀)alkanoyl, (C₃-C₈)cycloalkyl, aryl, heteroaryl, aryl(C₁ -C₁₀)alkyl, heteroaryl(C₁-C₁₀)alkyl, or --CH₂ R_(i), wherein R_(i) is halo, cyano, cyanato,--OR_(j), --NR_(k) R_(l), azido, --SR_(m), or (C₃ -C₈)cycloalkyl; R⁴ ishydrogen, (C₁ -C₁₀)alkyl, (C₃ -C₈)cycloalkyl, (C₂ -C₁₀)alkenyl, (C₂-C₁₀)alkynyl, aryl, or heteroaryl; m and n are each independently 0, 1,or 2; each R_(a) -R_(f) is independently hydrogen, (C₁ -C₁₀)alkyl, (C₃-C₈)cycloalkyl, (C₂ -C₁₀)alkenyl, (C₂ -C₁₀)alkynyl, aryl, heteroaryl,oxazolidinyl, isoxazolidinyl, or morpholinyl; each R_(g) or R_(h) isindependently hydrogen, (C₁ -C₁₀)alkyl, (C₃ -C₈)cycloalkyl, (C₂-C₁₀)alkenyl, (C₂ -C₁₀)alkynyl, (C₁ -C₁₀)alkanoyl, aryl, benzyl,phenethyl, heteroaryl oxazolidinyl, isoxazolidinyl, or morpholinyl; orR_(g) and R_(h) together with the nitrogen to which they are attachedare triazolyl, imidazolyl, oxazolidinyl, isoxazolidinyl, pyrrolyl,morpholino, piperidino, pyrrolidino, pyrazolyl, indolyl, or tetrazolyl;R_(j) is hydrogen, (C₁ -C₁₀)alkyl, (C₃ -C₈)cycloalkyl, (C₂ -C₁₀)alkenyl,(C₂ -C₁₀)alkynyl, --C(═O)N(R_(p))₂, aryl, heteroaryl, arylcarbonyl,heteroarylcarbonyl, or (C₁ -C₁₀)alkanoyl, wherein each R_(p) isindependently hydrogen, (C₁ -C₁₀)alkyl, aryl, benzyl, phenethyl, orheteroaryl; each R_(k) or R_(l) is independently hydrogen, (C₁-C₁₀)alkyl, (C₃ -C₈)cycloalkyl, (C₂ -C₁₀)alkenyl, (C₂ -C₁₀)alkynyl, (C₁-C₁₀)alkanoyl, --C(═O)N(R_(q))₂, aryl, benzyl, phenethyl, heteroaryloxazolidinyl, isoxazolidinyl, or morpholinyl, wherein each R_(q) isindependently hydrogen, (C₁ -C₁₀)alkyl, aryl, benzyl, phenethyl, orheteroaryl; or R_(k) and R_(l) together with the nitrogen to which theyare attached are triazolyl, imidazolyl, oxazolidinyl, isoxazolidinyl,pyrrolyl, morpholino, piperidino, pyrrolidino, pyrazolyl, indolyl, ortetrazolyl; and R_(m) is hydrogen, (C₁ -C₁₀)alkyl, (C₃ -C₈)cycloalkyl,(C₂ -C₁₀)alkenyl, (C₂ -C₁₀)alkynyl, cyano, aryl, benzyl, phenethyl,heteroaryl, oxazolidinyl, isoxazolidinyl, or morpholinyl; wherein any(C₁ -C₁₀)alkyl, (C₃ -C₈)cycloalkyl, (C₂ -C₁₀)alkenyl, (C₂ -C₁₀)alkynyl,(C₁ -C₁₀)alkanoyl, aryl, benzyl, phenethyl, heteroaryl, arylcarbonyl,heteroarylcarbonyl, oxazolidinyl, isoxazolidinyl, or morpholinyl of R¹-R⁴, R_(a) -R_(m), or R_(p) -R_(q), may optionally be substituted with1, 2, or 3 Z; and each Z is independently halo, nitro, cyano, hydroxy,(C₁ -C₁₀)alkyl, (C₃ -C₈)cycloalkyl, (C₁ -C₁₀)alkoxy, (C₁ -C₁₀)alkanoyl,(C₂ -C₁₀)alkanoyloxy, trifluoromethyl, aryl, aryloxy, heteroaryl, or--SR_(n), wherein R_(n) is hydrogen, (C₁ -C₁₀)alkyl, (C₃ -C₈)cycloalkyl,aryl, benzyl, phenethyl, or heteroaryl; and further wherein any aryl,aryloxy, heteroaryl, benzyl, or phenethyl of Z may optionally besubstituted with 1, 2, or 3 substituents selected from the groupconsisting of halo, nitro, cyano, hydroxy, (C₁ -C₁₀)alkyl, (C₃-C₈)cycloalkyl, (C₁ -C₁₀)alkoxy, (C₁ -C₁₀)alkanoyl, (C₂-C₁₀)alkanoyloxy, and trifluoromethyl; or a pharmaceutically acceptablesalt thereof.

Another prefered compound is a compound of formula (I) wherein: R¹ ishydrogen; R² is (C₁ -C₁₀)alkyl, --COOR_(a), --CONR_(b) R_(c), cyano,--C(═O)R_(d), --OR_(e), aryl, heteroaryl, oxazolidinyl, isoxazolidinyl,morpholinyl, --S(O)_(m) R_(f), --NR_(g) R_(h), azido, or halo; R³ is (C₂-C₁₀)alkenyl, (C₂ -C₁₀)alkynyl, (C₁ -C₁₀)alkanoyl, or --CH₂ R_(i),wherein R_(i) is halo, cyano, cyanato, --OR_(j), --NR_(k) R_(l), azido,--SR_(m), or (C₃ -C₈)cycloalkyl; R⁴ is hydrogen, (C₁ C₁₀)alkyl, (C₃-C₈)cycloalkyl, (C₂ -C₁₀)alkenyl, (C₂ -C₁₀)alkynyl, aryl, or heteroaryl;m and n are each independently 0, 1, or 2; each R_(a) -R_(f) isindependently hydrogen, (C₁ -C₁₀)alkyl, (C₃ -C₈)cycloalkyl, (C₂-C₁₀)alkenyl, (C₂ -C₁₀)alkynyl, aryl, or heteroaryl; each R_(g) or R_(h)is independently hydrogen, (C₁ -C₁₀)alkyl, (C₃ -C₈)cycloalkyl, (C₂-C₁₀)alkenyl, (C₂ -C₁₀)alkynyl, (C₁ C₁₀ alkanoyl, aryl, benzyl,phenethyl, or or R_(g) and R_(h) together with the nitrogen to whichthey are attached are morpholino, piperidino, or pyrrolidino; R_(j) ishydrogen, (C₁ -C₁₀)alkyl, (C₃ -C₈)cycloalkyl, (C₂ -C₁₀)alkenyl, (C₂-C₁₀)alkynyl, --C(═O)N(R_(p))₂, aryl, heteroaryl, arylcarbonyl,heteroarylcarbonyl, or (C₁ -C₁₀)alkanoyl, wherein each R_(p) isindependently hydrogen, (C₁ -C₁₀)alkyl, aryl, benzyl, phenethyl, orheteroaryl; each R_(k) or R_(l) is independently hydrogen, (C₁-C₁₀)alkyl, (C₁ -C₁₀)alkanoyl, aryl, benzyl, or phenethyl; or R_(k) andR_(l) together with the nitrogen to which they are attached aremorpholino, piperidino, or pyrrolidino; and R_(m) is hydrogen, (C₁-C₁₀)alkyl, (C₃ -C₈)cycloalkyl, (C₂ -C₁₀)alkenyl, or (C₂ -C₁₀)alkynyl;wherein any (C₁ -C₁₀)alkyl, (C₁ -C₁₀)alkanoyl, aryl, benzyl, phenethyl,heteroaryl, arylcarbonyl, or heteroarylcarbonyl of R¹ -R⁴, R_(a) -R_(m),or R_(p), may optionally be substituted with 1, 2, or 3 Z; and each Z isindependently halo, nitro, cyano, hydroxy, (C₁ -C₁₀)alkyl, (C₁-C₁₀)alkoxy, (C₁ -C₁₀)alkanoyl, (C₂ -C₁₀)alkanoyloxy, trifluoromethyl,aryl, aryloxy, heteroaryl, or --SR_(n), wherein R_(n) is hydrogen, (C₁-C₁₀)alkyl, (C₃ -C₈)cycloalkyl, aryl, benzyl, phenethyl, or heteroaryl;and further wherein any aryl, aryloxy, heteroaryl, benzyl, or phenethylof Z may optionally be substituted with 1, 2, or 3 substituents selectedfrom the group consisting of halo, nitro, cyano, hydroxy, (C₁-C₁₀)alkyl, (C₁ -C₁₀)alkoxy, (C₁ -C₁₀)alkanoyl, (C₂ -C₁₀)alkanoyloxy,and trifluoromethyl; or a pharmaceutically acceptable salt thereof.

Processes and novel intermediates useful for preparing compounds offormula I are provided as further embodiments of the invention and areillustrated by the following procedures in which the meanings of thegeneric radicals are as given above unless otherwise qualified. Certaincompounds of formula (I) are also useful as intermediates for preparingother compounds of formula (I).

A compound of formula I (wherein R¹ is hydrogen, R⁴ is diphenylmethyland n is 0, formula 6) can be prepared by treatment of a correspondingcompound of formula 5 with silver acetate and the requisite carboxylicacid in dichloromethane, as illustrated in FIG. 1. The reaction canconveniently be carried out as described in Examples 1-6. In general, acompound of formula (I) can be prepared from a corresponding compound offormula 18 by treatment with a requsite acid of formula R² CO₂ H in thepresence of a suitable catalyst (e.g. silver acetate). The reaction canconveniently be carried out under conditions similar to those describedin Examples 1-6 and 34 hereinbelow.

A compound of formula I wherein R³ is hydroxymethyl may also be preparedfrom a corresponding compound of formula I wherein R³ ischloroacetoxymethyl by treatment with thiourea in the presence of asuitable base, such as for example, pyridine (T. Greene, P. Wutz"Protective Groups in Organic Synthesis, Second Edition; John Wiley andSons, Inc.; New York, 1991, p. 92). The reaction can conveniently becarried out in a suitable solvent, such as dimethylformamide, asillustrated in FIG. 4 for the conversion of compound 6b to compound 13.

A compound of formula I wherein R³ is halomethyl can be prepared from acorresponding compound of formula I wherein R³ is hydroxymethyl usingtechniques that are well known in the art, for example techniques suchas those described in Jerry March "Advanced Organic Chemistry" JohnWiley & Sons, 4 ed. 1992, 431-433.

A compound of formula I wherein R³ is cyanomethyl can be prepared from acorresponding compound of formula I wherein R³ is halomethyl usingtechniques that are well known in the art, for example techniques suchas those described in Jerry March "Advanced Organic Chemistry" JohnWiley & Sons, 4 ed. 1992, 482.

A compound of formula I wherein R³ is cyanatomethyl can be prepared froma corresponding compound of formula I wherein R³ is hydroxymethyl byreaction with a cyanogen halide using techniques that are well known inthe art, for example techniques such as those described in Jerry March"Advanced Organic Chemistry" John Wiley & Sons, 4 ed.1992, 387.

A compound of formula I wherein R³ is --CH₂ OR, can be prepared from acorresponding compound of formula I wherein R³ is --CH₂ (halo) byreaction with the requisite alcohol HOR_(i) using techniques that arewell known in the art, for example techniques such as those described inJerry March "Advanced Organic Chemistry" John Wiley & Sons, 4 ed.1992,386-387.

A compound of formula I wherein R³ is --CH₂ NR_(j) R_(k) can be preparedfrom a corresponding compound of formula I wherein R³ is --CH₂ (halo)using techniques that are well known in the art, for example techniquessuch as those described in Jerry March "Advanced Organic Chemistry" JohnWiley & Sons, 4 ed.1992, 411-413, 425-427.

A compound of formula I wherein R³ is azidomethyl can be prepared from acorresponding compound of formula I wherein R³ is --CH₂ (halo) usingtechniques that are well known in the art, for example techniques suchas those described in Jerry March "Advanced Organic Chemistry" JohnWiley & Sons, 4 ed.1992, 411-413, 428-429.

A compound of formula I wherein R³ is --CH₂ SR_(i) can be prepared froma corresponding compound of formula I wherein R³ is --CH₂ (halo) byreaction with the requisite thiol HSR_(i) using techniques that are wellknown in the art, for example techniques such as those described inJerry March "Advanced Organic Chemistry" John Wiley & Sons, 4 ed. 1992,407.

A compound of formula I wherein n is 2 (formula 7) can be prepared byoxidation of a corresponding compound of formula I wherein n is 0, forexample, by using meta-chloroperbenzoic acid (mCPBA), as illustrated inFIG. 1 for the conversion of a compound of formula 6 to a compound offormula 7.

A compound of formula I wherein n is 1 can be prepared by oxidation of acorresponding compound of formula I wherein n is 0, using one equivalentof an acceptable oxidizing agent, for example, mCPBA.

A compound of formula I wherein R⁴ is hydrogen can generally be preparedfrom a corresponding ester of formula I wherein R⁴ is other thanhydrogen by hydrolysis, using techniques which are well known in theart, as illustrated in FIG. 2 for the conversion of a compound offormula 7 to a compound of formula 8.

A compound of formula I wherein R² is carboxy can be prepared from acorresponding ester of formula I by hydrolysis, using techniques whichare well known in the art, as illustrated in FIG. 2 for the conversionof a compound of formula 7 to a compound of formula 8.

A compound of formula I wherein R¹ is carboxy can be prepared from acorresponding ester of formula I by hydrolysis, using techniques whichare well known in the art.

A compound of formula I wherein R³ is(1-methyl-1H-tetrazol-5-yl)thioacetoxymethyl can be prepared from acorresponding compound of formula I wherein R³ is chloroacetoxymethyl byreaction with 1-methyl-1H-tetrazol-5-ylmercaptan using techniques whichare well known in the art, as illustrated in FIG. 2 for the conversionof a compound of formula 7b to a compound of formula 7g. For Example,the reaction can conveniently be carried out as described in Example 13or 14.

A compound of formula I wherein R³ is chloromethyl (formula 10) can beprepared from a corresponding compound of formula 5 as illustrated inFIG. 3, by treatment with copper II chloride in a suitable solvent. Forexample, the reaction can conveniently be carried out as described inExample 22 or 23.

A compound of formula I wherein R³ is formyl can be prepared from acorresponding compound of formula I wherein R³ is hydroxymethyl byoxidation, using techniques which are well known in the art, asillustrated in FIG. 4 for the conversion of a compound of formula 13 toa compound of formula 14. The reaction can conveniently be carried outby treating an alcohol of formula 13 with oxalyl chloride in thepresence of dimethylsulfoxide and a suitable base, such astriethylamine, as described in Example 30.

A compound of formula I wherein R³ is a 1-alkenyl substituent cangenerally be prepared from a corresponding compound of formula I whereinR³ is formyl, by reaction with the requisite ylide or stabilized ylide,using techniques which are well known in the art, as illustrated in FIG.4 for the conversion of a compound of formula 14 to a compound offormula 15.

As illustrated in FIG. 7, compound 6i can be prepared from compound 5aby treatment with 3,4-di-(4-methoxybenzyloxy)phenylacetic acid andsilver acetate under conditions similar to those described in Example 6.Oxidation with mCPBA under conditions similar to those described inExample 12 gives a sulfoxide of formula 7i. Deprotection of compound 7iunder standard conditions (e.g. similar to those described in Example21) gives the diacid of formula (I), which can be converted to thedisalt of formula 8i by treatment with a suitable base (e.g. sodiumbicarbonate) under standard conditions.

As illustrated in FIG. 8, a compound of formula 29a or 29b can beprepared from 6-Aminopenicillinic acid (6-APA) by formation of thebenzyl or benzhydryl ester, to give a compound of formula 19a or 19b.Reaction with allyl chloroformate gives the N-allyloxycarbonylderivative 20a or 20b. Oxidation of the sulfide to the sulfoxide givescompounds 21a and 21b, which can be heated with mercaptobenzothiazole toproduce the ring opened disulfides 22a and 22b. Compound 22a was thentreated with an excess of acetic acid in the presence of 2 eq of AgOActo produce a 4:1 mixture of the 2β-substituted penam 23a and the cepham24a. Likewise compound 22b was treated with an excess of phenylaceticacid in the presence of 2 eq of AgOAc to produce a 4:1 mixture of the2β-substituted penam 23b and the corresponding cepham 24b, respectively.These mixtures were separated to give the purified penams 23a and 23b,which were deprotected at nitrogen by reaction with (n-Bu)₃ SnH in thepresence of a catalytic amount of Pd(PPh₃)₄ to give amines, 25a and 25b.Treatment with isopropyl nitrite gives the corresponding diazocompounds,which were immediately converted to the corresponding ketones byreaction with excess propylene oxide in the presence of a catalyticamount of Rh₂ OAc₄. The ketones were derivatized by reaction with theWittig reagent [(2-pyridyl)methylene]triphenylphosporane to producealkenes 27a and 27b, which were oxidized with excess MCPBA to producesulfones 28a and 28b. Sulfone 28a was deprotected by reaction with LiIin refluxing EtOAc to produce sodium salt 29a. Sulfone 28b wasdeprotected by reaction with trifluoroacetic acid in anisole, andsubsequent treatment with sodium bicarbonate, to produce sodium salt29b.

A useful intermediate for the preparation of a compound of the inventionis a compound of formula 18. As illustrated in FIG. 5, a compound offormula 18 can be prepared by treatment of 6-oxopenicillinate 2(Hagiwara, D. F.; Sawada, K.; Ohnami, T.; Aratani, M.; Hashimoto, M., J.Chem. Soc. Chem. Commun., 578 (1982)) with a compound of formula R¹ R²C═PPh₃ to give a 6-alkylidene penicillinate of formula 3. Reaction of acompound of formula 3 with 1 equivalent of mCPBA in CH₂ Cl₂ gives asulfoxide of formula 4, which can be heated to reflux in toluene in thepresence of 2-mercaptobenzothiazole to obtain the disulfide of formula(18).

Another useful intermediate for the preparation of a compound of theinvention is an ylide, for example a ylide of formula R¹ R² C═PPh₃.Ylides can be prepared using techniques that are well known in the art,for example techniques such as those described in Jerry March "AdvancedOrganic Chemistry" John Wiley & Sons, 4 ed. 1992, 956-963. Suitableylides are also disclosed in U.S. Pat. No. 5,597,817, issued Jan. 29,1997; and U.S. Pat. No. 5,629,306, issued May 13, 1997.

It is noted that many of the starting materials employed in thesynthetic methods described above are commercially available or arereported in the scientific literature. It is also noted that it may bedesirable to optionally use a protecting group during all or portions ofthe above described synthetic procedures. Such protecting groups andmethods for their introduction and removal are well known in the art(see Greene, T. W.; Wutz, P. G. M. "Protecting Groups In OrganicSynthesis" second edition, 1991, New York, John Wiley & sons, Inc.).

In cases where compounds are sufficiently basic or acidic to form stablenontoxic acid or base salts, administration of the compounds as saltsmay be appropriate. Examples of pharmaceutically acceptable salts areorganic acid addition salts formed with acids which form a physiologicalacceptable anion, for example, tosylate, methanesulfonate, acetate,citrate, malonate, tartarate, succinate, benzoate, ascorbate,α-ketoglutarate, and α-glycerophosphate. Suitable inorganic salts mayalso be formed, including hydrochloride, sulfate, nitrate, bicarbonate,and carbonate salts.

Pharmaceutically acceptable salts may be obtained using standardprocedures well known in the art, for example, by reacting asufficiently basic compound such as an amine with a suitable acidaffording a physiologically acceptable anion. Alkali metal (for example,sodium, potassium or lithium) or alkaline earth metal (for example,calcium) salts of carboxylic acids can also be made.

Prefered salts of the invention include disalts prepared from acids offormula (I) wherein R¹ or R² is carboxy and R⁴ is hydrogen. Preferedsalts also include monosalts (e.g. a sodium salt) prepared from an acidof formula (I) wherein R⁴ is hydrogen. The invention also provides amethod for preparing a compound of the invention comprising forming amono-, di-, or tri-salt from a coresponding compound of formula (I).

The compounds of formula I can be formulated as pharmaceuticalcompositions and administered to a mammalian host, such as a humanpatient in a variety of forms adapted to a selected route ofadministration, i.e., by oral, parenteral, intravenous, intramuscular,topical, or subcutaneous routes.

Thus, the present compounds may be systemically administered, e.g.,orally, in combination with a pharmaceutically acceptable vehicle suchas an inert diluent or an assimilable edible carrier. They may beenclosed in hard or soft shell gelatin capsules, may be compressed intotablets, or may be incorporated directly with the food of the patient'sdiet. For oral therapeutic administration, the active compound may becombined with one or more excipients and used in the form of ingestibletablets, buccal tablets, troches, capsules, elixirs, suspensions,syrups, wafers, and the like. Such compositions and preparations shouldcontain at least 0.1% of active compound. The percentage of thecompositions and preparations may, of course, be varied and mayconveniently be between about 2 to about 60% of the weight of a givenunit dosage form. The amount of active compound in such therapeuticallyuseful compositions is such that an effective dosage level will beobtained.

The tablets, troches, pills, capsules, and the like may also contain thefollowing: binders such as gum tragacanth, acacia, corn starch orgelatin; excipients such as dicalcium phosphate; a disintegrating agentsuch as corn starch, potato starch, alginic acid and the like; alubricant such as magnesium stearate; and a sweetening agent such assucrose, fructose, lactose or aspartame or a flavoring agent such aspeppermint, oil of wintergreen, or cherry flavoring may be added. Whenthe unit dosage form is a capsule, it may contain, in addition tomaterials of the above type, a liquid carrier, such as a vegetable oilor a polyethylene glycol. Various other materials may be present ascoatings or to otherwise modify the physical form of the solid unitdosage form. For instance, tablets, pills, or capsules may be coatedwith gelatin, wax, shellac or sugar and the like. A syrup or elixir maycontain the active compound, sucrose or fructose as a sweetening agent,methyl and propylparabens as preservatives, a dye and flavoring such ascherry or orange flavor. Of course, any material used in preparing anyunit dosage form should be pharmaceutically acceptable and substantiallynon-toxic in the amounts employed. In addition, the active compound maybe incorporated into sustained-release preparations and devices.

The active compound may also be administered intravenously orintraperitoneally by infusion or injection. Solutions of the activecompound or its salts can be prepared in water, optionally mixed with anontoxic surfactant. Dispersions can also be prepared in glycerol,liquid polyethylene glycols, triacetin, and mixtures thereof and inoils. Under ordinary conditions of storage and use, these preparationscontain a preservative to prevent the growth of microorganisms.

The pharmaceutical dosage forms suitable for injection or infusion caninclude sterile aqueous solutions or dispersions or sterile powderscomprising the active ingredient which are adapted for theextemporaneous preparation of sterile injectable or infusible solutionsor dispersions, optionally encapsulated in liposomes. In all cases, theultimate dosage form must be sterile, fluid and stable under theconditions of manufacture and storage. The liquid carrier or vehicle canbe a solvent or liquid dispersion medium comprising, for example, water,ethanol, a polyol (for example, glycerol, propylene glycol, liquidpolyethylene glycols, and the like), vegetable oils, nontoxic glycerylesters, and suitable mixtures thereof. The proper fluidity can bemaintained, for example, by the formation of liposomes, by themaintenance of the required particle size in the case of dispersions orby the use of surfactants. The prevention of the action ofmicroorganisms can be brought about by various antibacterial andantifungal agents, for example, parabens, chlorobutanol, phenol, sorbicacid, thimerosal, and the like. In many cases, it will be preferable toinclude isotonic agents, for example, sugars, buffers or sodiumchloride. Prolonged absorption of the injectable compositions can bebrought about by the use in the compositions of agents delayingabsorption, for example, aluminum monostearate and gelatin.

Sterile injectable solutions are prepared by incorporating the activecompound in the required amount in the appropriate solvent with variousof the other ingredients enumerated above, as required, followed byfilter sterilization. In the case of sterile powders for the preparationof sterile injectable solutions, the preferred methods of preparationare vacuum drying and the freeze drying techniques, which yield a powderof the active ingredient plus any additional desired ingredient presentin the previously sterile-filtered solutions.

For topical administration, the present compounds may be applied in pureform, i.e., when they are liquids. However, it will generally bedesirable to administer them to the skin as compositions orformulations, in combination with a dermatologically acceptable carrier,which may be a solid or a liquid.

Useful solid carriers include finely divided solids such as talc, clay,microcrystalline cellulose, silica, alumina and the like. Useful liquidcarriers include water, alcohols or glycols or water-alcohol/glycolblends, in which the present compounds can be dissolved or dispersed ateffective levels, optionally with the aid of non-toxic surfactants.Adjuvants such as fragrances and additional antimicrobial agents can beadded to optimize the properties for a given use. The resultant liquidcompositions can be applied from absorbent pads, used to impregnatebandages and other dressings, or sprayed onto the affected area usingpump-type or aerosol sprayers.

Thickeners such as synthetic polymers, fatty acids, fatty acid salts andesters, fatty alcohols, modified celluloses or modified mineralmaterials can also be employed with liquid carriers to form spreadablepastes, gels, ointments, soaps, and the like, for application directlyto the skin of the user.

Examples of useful dermatological compositions which can be used todeliver the compounds of formula I to the skin are disclosed in Jacquetet al. (U.S. Pat. No. 4,608,392), Geria (U.S. Pat. No. 4,992,478), Smithet al. (U.S. Pat. No. 4,559,157) and Wortzman (U.S. Pat. No. 4,820,508).

Useful dosages of the compounds of formula I can be determined bycomparing their in vitro activity, and in vivo activity in animalmodels. Methods for the extrapolation of effective dosages in mice, andother animals, to humans are known to the art; for example, see U.S.Pat. No. 4,938,949.

Generally, the concentration of the compound(s) of formula I in a liquidcomposition, such as a lotion, will be from about 0.1-25 wt-%,preferably from about 0.5-10 wt-%. The concentration in a semi-solid orsolid composition such as a gel or a powder will be about 0.1 -5 wt-%,preferably about 0.5-2.5 wt-%. Single dosages for injection, infusion oringestion will generally vary between 50-1500 mg, and may beadministered, i.e., 1-3 times daily, to yield levels of about 0.5-50mg/kg, for adults.

Accordingly, the invention provides a pharmaceutical composition,comprising an effective amount of a compound of formula I as describedhereinabove; or a pharmaceutically acceptable salt thereof; and apharmaceutically acceptable carrier. The invention also provides apharmaceutical composition comprising an effective amount of a compoundof formula I, as described hereinabove; or a pharmaceutically acceptablesalt thereof; a β-lactam antibiotic; and a pharmaceutically acceptablecarrier. Any β-Lactam antibiotic is suitable for use in thepharmaceutical composition of the invention. β-Lactam antibiotics whichare well known in the art include those disclosed by R. B. Morin and M.Gorin, M.Eds.; Academic Press, New York, 1982; vol. 1-3. Preferredβ-Lactam antibiotics, suitable for use in the pharmaceutical compositionof the invention, include β-lactam antibiotics which are preferentiallydeactivated by Class A and Class C β-lactamase enzymes, for example,amoxicillin, piperacillin, ampicillin, ceftizoxime, cefotaxime,cefuroxime, cephalexin, cefaclor, cephaloridine, and ceftazidime.

The ability of a compound of the invention to function as a β-lactamaseinhibitor can be demonstrated using the test described below, or usingother tests which are well known in the art.

Representative compounds of the invention, as well as the knowncommercial inhibitors clavulanic acid and tazobactam, and the previouslyreported 2β-methyl compound 9 (Buynak et al., Bioorg. Med. Chem. Lett.,5, 1513 (1995)) (see FIG. 6 for structures) were evaluated as inhibitorsof the β-lactamase of Enterobacter cloacae P99 and TEM-1. The IC₅₀ valueof each compound was determined as follows. Following a 10 minuteincubation of a dilute solution of enzyme (2.56 nM) and inhibitor (<0.64μM), a 50 μL aliquot of the incubation mixture was further diluted into1 mL nitrocefin (a substrate) solution, and the rate of hydrolysis wasmeasured during a 1 minute period by monitoring the absorbance ofnitrocefin as a function of time.

The results are summarized in Table 1. The β-lactamase inhibitingactivity of compound 8a, 8b, 8d, and 8g is greater than the activity ofcompound 9 by at least a factor of 10 for TEM-1; and the β-lactamaseinhibiting activity of compound 8a and 8c is greater than the activityof compound 9 by a factor of nearly 2 for P99. Compounds 8a, 8b, 8d, and8g are also more active than the current commercial inhibitorsclavulanic acid and tazobactam. In addition, compounds 29a and 29bdemonstrate potent β-lactamase inhibiting activity against TEM-1 andP99.

                  TABLE 1                                                         ______________________________________                                        β-Lactamase Inhibitory Activity                                                              IC.sub.50 (μM)                                            Ent. cloacae IC.sub.50 (μM)                                               Compounds P99 TEM-1                                                         ______________________________________                                        tazobactam      17.2      0.32                                                  clavulanic acid >20000 60                                                     8a 0.383 0.213                                                                8b NT 0.19                                                                    8c 0.30 1.84                                                                  8d 0.54 0.015                                                                 8e 2.66 2.72                                                                  8g 0.64 0.23                                                                  8h 3.69 2.37                                                                  8i 0.37 0.105                                                                 9 0.75 2.51                                                                   12a 7.62 39.0                                                                 12b 6.96 44.5                                                                 12c 105.4 120.5                                                               17 6.76 21.62                                                                 29a 0.062 0.004                                                               29b NT 0.39                                                                 ______________________________________                                    

Compounds of the invention have been shown to possess activity asβ-lactamase inhibitors. Accordingly, the invention provides a methodcomprising inhibiting a β-lactamase by contacting said β-lactamase withan effective amount of a compound of formula I; or a pharmaceuticallyacceptable salt thereof. The β-lactamase may be contacted with thecompound of claim in vitro or in vivo.

The invention also provides a therapeutic method comprising inhibiting aβ-lactamase in a mammal (preferably a human) in need of such therapy, byadministering an effective inhibitory amount of a compound of formula I;or a pharmaceutically acceptable salt thereof.

Because compounds of the invention inhibit β-lactamase enzymes, they mayalso be useful to increase the effectiveness of β-lactam antibioticswhich arc degraded by such enzymes. Accordingly, the invention providesa method comprising enhancing (increasing by a detectable amount) theactivity of a β-lactam antibiotic, by administering the β-lactamantibiotic to a mammal (preferably a human) in need thereof, incombination with an effective amount of a compound of formula I; or apharmaceutically acceptable salt thereof.

The invention also provides a method comprising treating a β-lactamresistant bacterial infection in a mammal (preferably a human), byadministering an effective amount of a β-lactam antibiotic incombination with an effective β-lactamase inhibiting amount of acompound of formula I; or a pharmaceutically acceptable salt thereof.

Additionally, the invention provides a compound of formula I for use inmedical therapy (preferably for use in treating a β-lactam resistantinfection), as well as the use of a compound of formula I for themanufacture of a medicament useful for reducing β-lactamase activity ina mammal.

Compounds of the invention possess specific 6-alkylidene substituentsand specific 2β-substituents. This combination of structural featuresprovides compounds that can exhibit extremely high activity asinhibitors of β-lactamase. Additionally, compounds of the invention maypossess other biological or pharmacological properties which make themsuperior to known compounds as therapeutic agents.

The invention will now be illustrated by the following non-limitingexamples.

EXAMPLE 1 Benzhydryl2β-(acetoxymethyl)-6-[(Z)-(t-butoxycarbonyl)methylene]penicillinate (6a)

To a solution of a compound of formula 5a (0.70 g, 1.086 mmol) in CH₂Cl₂ were added AcOH (2.78 g, 46.68 mmol) and AgOAc (0.376 g, 2.26 mmol)and the reaction was stirred for 4 hours. The reaction mixture was thenfiltered through a celite bed and the filtrate was washed with asaturated NaHCO₃ solution. The organic layer was dried (Na₂ SO₄),concentrated, and purified by flash column chromatography to yield thetitle compound 6a (390 mg, 66.8%). ¹ H NMR (CDCl₃): δ 7.39-7.26 (10H,m), 6.95 (1H, s), 6.18 (1H, s), 6.01 (1H, s), 4.95 (1H, s), 4.12 (1H,d), 3.77 (1H, d), 2.09 (3H, s), 1.51 (9H, s), 1.24 (3H, s).

The intermediate of formula 5a was prepared as follows.

a. Benzhydryl 6-[(Z)-t-butoxycarbonylmethylene]penicillinate (3a).

To a solution of (3.6 g, 9.4 mmol) benzhydryl 6-oxopenicillinate,compound 2, (J. D. Buynak et al., J. Org. Chem., 58, 1325-1335 (1993))in 50 mL anhydrous CH₂ Cl₂ at -78° C., was added a solution of(tert-butoxycarbonylmethylene) triphenylphosphorane (3.6 g, 9.56 mmol)in an additional 50 mL anhydrous CH₂ Cl₂. The reaction was allowed tostir for 80 minutes at -78° C., then poured into a separatory funnelcontaining 400 mL cold saturated aqueous NH₄ Cl. The layers wereseparated and the aqueous layer was extracted a second time with 50 mLCH₂ Cl₂. The combined organic layers were dried (Na₂ SO₄) andconcentrated. The resulting material was further purified by columnchromatography (SiO₂, CH₂ Cl₂) to yield a white foam (2.38 g, 53%yield). ¹ H NMR (CDCl₃): δ 7.40-7.27 (10H, m), 6.93 (1H, s), 6.17 (1H,d, J=4 Hz), 5.97 (1H, d, J=4 Hz), 4.63 (1H, s), 1.54 (3H, s), 1.49 (9H,s), 1.25 (3H, s).

b. Benzhydryl 6-[(Z)-t-butoxycarbonyl)methylene]penicillinate sulfoxide(4a).

To a solution of benzhydryl 6-[(Z)-(t-butoxycarbonyl)methylene]penicillinate, compound 3a, (4.5 g, 9.349 mmol) in CH₂ Cl₂ was addedmCPBA (2.32 g, 9.394 mmol) in one portion and the reaction mixture wasstirred for 1 hour at room temperature. The reaction mixture was washedwith NaHCO₃ solution, dried over Na₂ SO₄, concentrated and purified bycolumn chromatography to give 5:1 mixtures of β:α sulfoxides (2.93 g,63%). ¹ H NMR (CDCl₃) of β-sulfoxide: δ 7.37-7.31 (10H, m), 7.00 (1H,s), 6.50 (1H, s), 5.67 (1H, s), 4.77 (1H, s), 1.67 (3H, s), 1.52 (9H,s), 0.98 (3H, s). ¹ H NMR of α-sulfoxide: δ 7.37-7.31 (10H, m), 7.00(1H, s), 6.02 (1H, s), 5.33 (1H, s), 4.79 (1H, s), 1.68 (3H, s), 1.51(9H, s), 0.96 (3H, s).

c.4-(2'-Benzothiazolyldithio)-3-[(Z)-(t-butoxycarbonyl)methylene]-1-[1'-diphenylmethyloxycarbonyl-2'-methylprop-2'-enyl]azetidin-2-one(5a).

To a solution of benzhydryl 6-[(Z)-(t-butoxycarbonyl)methylene]penicillinate sulfoxide, compound 4, (2.35 g, 4.74 mmol) in toluene, wasadded 2-mercaptobenzothiazole (0.792 g, 4.74 mmol) and the reaction washeated to reflux for 4.5 hours. Volatiles were removed under reducedpressure to give compound 5a (3.15 g, 100%). ¹ H NMR (CDCl₃): δ 7.86(1H, d, J=8 Hz), 7.71 (1H, d, J=8 Hz), 7.42-7.25 (12H, m), 6.88 (1H, s),6.09 (1H, s), 5.96 (1H, s), 5.14 (1H, s), 5.12 (1H, s), 5.00 (1H, s),1.88 (3H, s), 1.49 (9H, s).

EXAMPLE 2 Benzhydryl2β-(chloroacetoxymethyl)-6-[(Z)-(t-butoxycarbonyl)methylene]penicillinate(6b)

A solution of 5a (2.3 g, 3.57 mmol), chloroacetic acid (14.4 g, 153mmol) and AgOAc (1.24 g, 7.4 mmol) in CH₂ Cl₂ (100 mL) was stirred for 5hours at room temperature. The reaction mixture was filtered andfiltrate was washed with saturated NaHCO₃ (2×100 mL). The organic layerwas dried (Na₂ SO₄), concentrated, and purified by column chromatography(4:1 CH₂ Cl₂ : hexane as eluent) to give the title compound; 1.4 g(69%); ¹ H NMR (CDCl₃): δ 7.39-7.30 (m, 10H), 6.95 (s, 1H), 6.19 (s,1H), 6.02 (s, 1H), 4.93 (s, 1H), 4.24 (d, J=11.6 Hz, 1H), 4.13 (d,J=14.8 Hz, 1H), 4.07 (d, J=14.8 Hz), 1H), 3.85 (d, J=11.6 Hz, 1H), 1.51(s, 9H), 1.26 (s, 3H).

EXAMPLE 3 Benzhydryl2β-(formyloxymethyl)-6-[(Z)-(t-butoxycarbonyl)methylene]penicillinate(6c)

A solution of 5a (1.5 g, 2.33 mmol), 97% formic acid (4.02 mL, 101.3mmol) and AgOAc (0.81 g, 4.84 mmol) in CH₂ Cl₂ (45 mL) was stirred for 5hours at room temperature. The reaction mixture was filtered and thefiltrate was washed with saturated aqueous NaHCO₃ (2×50 mL). The organiclayer was dried (Na₂ SO₄) and concentrated to yield a crude formate(1.05 g, 86%) which was directly oxidized to the sulfone.

EXAMPLE 4 Benzhydryl2β-(phenylacetoxymethyl)-6-[(Z)-(t-butoxycarbonyl)methylene]penicillinate(6d)

A mixture of disulfide 5a (2.0 g, 3.31 mmol), phenylacetic acid (19.4g,142.4 mmol) and AgOAc (1.15 g, 6.88 mmol) in CH₂ Cl₂ (80 mL) was stirredfor 5 hours at room temperature. The reaction mixture was filteredthrough celite and washed with aq NaHCO₃ solution (2×100 mL). Theorganic layer was dried (Na₂ SO₄), concentrated, and purified by columnchromatography to give the title compound 6d; 1.04 g, 51%; ¹ H NMR(CDCl₃): δ 7.37-7.23 (m, 15H), 6.94 (s, 1H), 6.16 (s, 1H), 5.99 (s, 1H),4.91 (s, 1H), 4.14 (d, J=11.9 Hz, 1H), 3.78 (d, J=11.9 Hz, 1H), 3.67(ABq, 2H), 1.51 (s, 9H), 1.15 (s, 3H).

EXAMPLE 5 Benzhydryl2β-(acetoxymethyl)-6-[(Z)-(methoxycarbonyl)methylene]penicillinate (6e)

A mixture of disulfide 5b (350 mg, 0.581 mmol), acetic acid (1.44 mL,25.27 mmol) and AgOAc (0.201 g, 1.21 mmol) in CH₂ Cl₂ (15 mL) wasstirred for 5 hours at room temperature. The reaction mixture wasfiltered through celite and washed with aq NaHCO₃ solution (2×20 mL).The organic layer was dried (Na₂ SO₄), concentrated, and purified bycolumn chromatography to give the title compound 6e; (190 mg, 75%; ¹ HNMR (CDCl₃): δ 7.32-7.18 (m, 10H), 6.89 (s, 1H), 6.22 (s, 1H), 5.99 (s,1H), 4.86 (s, 1H), 4.03 (d, J=11.8 Hz, 1H), 3.74-3.72 (m, 4H), 2.01 (s,3H), 1.15 (s, 3H).

The intermediate disulfide 5b was prepared as follows.

a. Benzhydryl 6-[(Z)-(methoxycarbonyl)methylene]penicillinate (3b).

To a solution of ketone 2 (2.0 g, 5.25 mmol), in anhydrous THF (20 mL)at -78° C. was added methyl (triphenylphosphoranylidene)acetate (1.75 g,5.25 mmol) in THF (20 mL) and the reaction mixture stirred at -78° C.for 45 min. The reaction mixture was poured onto saturated aqueous NH4Cl(50 mL) and extracted with dichloromethane (60 mL). The organic layerwas dried (Na₂ SO₄), concentrated, and purified on silica gelchromatography to produce 3b (1.35 g, 59%). ¹ H NMR (CDCl₃): δ 7.37-7.30(10H, m), 6.96 (1H, s), 6.30 (1H, s), 6.03 (1H, d, s), 4.66 (1H, s),3.81 (3H, s), 1.56 (3H, s), 1.27 (3H, s).

b. Benzhydryl 6-[(Z)-(methoxycarbonyl)methylene]penicillinate sulfoxide(4b).

To a solution of sulfide 3b (1.2 g, 2.75 mmol) in CH₂ Cl₂ (20 mL) wasadded 70% mCPBA (0.68 g, 2.75 mmol) and the reaction mixture was stirredfor 30 minutes at room temperature. The reaction mixture was then pouredinto saturated aqueous NaHCO₃ (30 mL), the organic layer separated,dried (Na₂ SO₄), concentrated, and purified by column chromatography toproduce 4b (1.10 g, 88%). ¹ H NMR of α-sulfoxide: δ 7.37-7.30 (10H, m),7.00 (1H, s), 6.59 (1H, s), 5.69 (1H, s), 4.78 (1H, s), 3.83 (s, 3H),1.67 (3H, s), 0.98 (3H, s).

C.4-(2'-Benzothiazolyldithio)-3-[(Z)-(methoxycarbonyl)methylene]-1-[1'-(diphenylmethyloxycarbonyl)-2'-methylprop-2'-enyl]azetidin-2-one(5b).

A mixture of sulfoxide 4b (1.1 g, 2.43 mmol) and 2-mercaptobenzothiazole(0.405 g, 2.43 mmol) in toluene (35 mL) was heated to reflux for 4hours. Volatiles were removed under vacuum to produce disulfide 5b (1.46g, 100%). ¹ H NMR (CDCl₃): δ 7.78 (1H, d, J=8.0 Hz), 7.62 (1H, d, J=8.0Hz), 7.35-7.06 (12H, m), 6.81 (1H, s), 6.09 (1H, s), 5.93 (1H, s), 5.06(1H, s), 5.05 (1H, s), 4.89 (1H, s), 3.60 (3H, s), 1.8 (3H, s).

EXAMPLE 6 Benzhydryl2p-(chloroacetoxymethyl)-6-[(Z)-(methoxycarbonyl)methylene]penicillinate(6f)

A mixture of disulfide 5b (2.0 g, 3.32 mmol), chloroacetic acid (13.42g, 142.82 mmol) and AgOAc (1.15 g, 6.91 mmol) in CH₂ Cl₂ (60 mL) wasstirred for 5 hours at room temperature. The reaction mixture wasfiltered through celite and washed with aq NaHCO₃ solution (2×100 mL).The organic layer was dried (Na₂ SO₄), concentrated, and purified bycolumn chromatography to give the title compound 6f; 1.2 g, 77%; ¹ H NMR(CDCl₃): δ 7.38-7.29 (m, 10H), 6.96 (s, 1H), 6.31 (s, 1H), 6.07 (s, 1H),4.94 (s, 1H), 4.20 (d, J=12.3 Hz, 1H), 4.11 (d, J=16.8 Hz, 1H), 4.08 (d,J=16.8 Hz, 1H), 3.85 (d, J=12.3 Hz, 1H), 3.81 (s, 3H), 1.24 (s, 3H).

EXAMPLE 7 Benzhydryl2β-(acetoxymethyl)-6-[(Z)-(t-butoxycarbonyl)methylene]penicillinate-1,1-dioxide(7a)

To a solution of benzhydryl2β-(acetoxymethyl)-6-[(Z)-(tert-butoxycarbonyl)methylene]penicillinate(290 mg, 0.54 mmol, 6a) in CH₂ Cl₂ (10 mL) and pH 6.4 phosphate buffersolution (10 mL) was added mCPBA (293 mg, 1.18 mmol). The mixture wasstirred at room temperature for 18 hours, and then diluted with CH₂ Cl₂(10 mL). The organic layer was washed with NaHCO₃ solution (25 mL),dried (Na₂ SO₄), concentrated and purified by column chromatography togive the title compound; 226 mg, 73%; ¹ H NMR (CDCl₃): δ 7.37-7.33 (10H,m), 6.97 (1H, s), 6.49 (1H, s), 5.47 (1H, s), 4.85 (1H, s), 4.51 d, J=),4.35 (1H, d, J=), 2.08 (3H, s), 1.54 (9H, s), 1.18 (3H, s); IR (CHCl₃):1799, 1751.7; ¹³ C NMR (CDCl₃): δ 169.76, 165.55, 165.03, 161.94,143.99, 138.65, 138.52, 128.87, 128.76, 128.54, 127.56, 127.13, 127.18,84.09, 79.67, 72.67, 65.63, 64.17, 60.90, 27.89, 20.56, 15.57.

EXAMPLE 8 Benzhydryl2β-(chloroacetoxymethyl)-6-[(Z)-(t-butoxycarbonyl)methylene]penicillinate1,1-dioxide (7b)

To a solution of sulfide 6b (1.29 g, 2.1 mmol) in CH₂ Cl₂ (30 mL) wasadded mCPBA (70%, 0.8 g, 4.62 mmol) in one portion followed by pH 6.4phosphate buffer solution (30 mL) and the reaction mixture was stirredovernight. The organic layer was separated, washed with saturatedaqueous NaHCO₃ (1×50 mL), dried (Na₂ SO₄), concentrated and purified bysilica gel chromatography (CH₂ Cl₂ as eluent) to give the title compound7b; 0.893 g, 70.5%; ¹ H NMR (CDCl₃): δ 7.39-7.30 (10H, m), 6.99 (1H, s),6.53 (1H, s), 5.50 (s, 1H), 4.86 (s, 1H), 4.61 (d, J=12.19 Hz, 1H), 4.47(d, J=12.19 Hz, 1H), 4.12 (d, J=15.18 Hz, 1H), 4.06 (d, J=15.18 Hz, 1H),1.54 (s, 9H), 1.27 (s, 3H).

EXAMPLE 9 Benzhydryl2β-(formyloxymethyl)-6-[(Z)-(t-butoxycarbonyl)methylene]-penicillinate1,1-dioxide (7c)

The crude formate 6c (1.05 g, 2.01 mmol) was dissolved in CH₂ Cl₂ (25mL) and mCPBA (70%, 1.385 g, 8.03 mmol) and pH 6.4 phosphate buffer (25mL) was added. The reaction mixture was stirred at room temperature for14 hours. The organic layer was separated, washed with aqueous saturatedNaHCO₃ (50 mL), dried (Na₂ SO₄), concentrated and purified by silica gelchromatography to give the title compound 7c; 0.76 g, 68%; ¹ H NMR(CDCl₃): δ 7.42-7.28 (m, 10H), 6.98 (s, 1H), 6.52 (s, 1H), 5.48 (s, 1H),4.81 (s, 1H), 4.59 (d, J=12.16 Hz, 1H), 4.49 (d, J=12.16 Hz, 1H), 1.51(s, 9H), 1.21 (s, 3H).

EXAMPLE 10 Benzhydryl2β-(phenylacetoxymethyl)-6-[(Z)-(1-butoxycarbonyl)methylene]penicillinate1,1-dioxide (7d)

To a solution of sulfide 6d (0.65 g, 1.06 mmol) in CH₂ Cl₂ (20 mL) wasadded mCPBA (70%, 0.58 g, 2.33 mmol) in one portion followed by pH 6.4phosphate buffer solution (20 mL) and the reaction mixture was stirredovernight. The organic layer was separated, washed with saturatedaqueous NaHCO₃ (1×20 mL), dried (Na₂ SO₄), concentrated and purified bysilica gel chromatography to give the title compound 7d; 0.490 g, 71.6%;¹ H NMR (CDCl₃): δ 7.37-7.26 (15H, m), 6.95 (1H, s), 6.47 (1H, s), 5.46(s, 1H), 4.80 (s, 1H), 4.54 (d, J=12.3 Hz, 1H), 4.36 (d, J=12.3 Hz, 1H),3.65 (s, 2H), 1.53 (s, 9H), 1.09 (s, 3H).

EXAMPLE 11 Benzhydryl2β-(acetoxymethyl)-6-[(Z)-(methoxycarbonyl)methylene]-penicillinate1,1-dioxide (7e)

To a solution of benzhydryl2β-(acetoxymethyl)-6-[(Z)-(methoxycarbonyl)-methylene]penicillinate (6e,190 mg, 0.43 mmol) in CH₂ Cl₂ (10 mL) and pH 6.4 phosphate buffersolution (10 mL) was added mCPBA (225 mg, 0.913 mmol). The mixture wasstirred at room temperature for 18 hours, and then diluted with CH₂ Cl₂(10 mL). The organic layer was washed with NaHCO₃ solution (25 mL),dried (Na₂ SO₄), concentrated and purified by column chromatography togive the title compound 7e; 140 mg, 68.9%, ¹ H NMR (CDCl₃): δ 7.39-7.23(10 1l, m), 6.98 (1H, s), 6.59 (1H, s), 5.46 (1H, s), 4.82 (1H, s), 4.57(1H, d, J=12.2 Hz), 4.37 (1H, d, J=12.2 Hz), 3.86 (s, 3H), 2.02 (3H, s),1.19 (3H, s).

EXAMPLE 12 Benzhydryl2β-(chloroacetoxymethyl)-6-[(Z)-(methoxycarbonyl)methylene]penicillinate1,1-dioxide (7f)

To a solution of benzhydryl2β-(chloroacetoxymethyl)-6-[(Z)-(methoxycarbonyl)methylene]penicillinate(6f, 1.2 g, 2.55 mmol) in CH₂ Cl₂ (20 mL) and pH 6.4 phosphate buffersolution (20 mL) was added mCPBA (70%, 1.38 g, 5.61 mmol). The mixturewas stirred at room temperature for 18 hours, and then diluted with CH₂Cl₂ (20 mL). The organic layer was washed with NaHCO₃ solution (50 mL),dried (Na₂ SO₄), concentrated and purified by column chromatography togive the title compound 7f; 920 mg, 72%; ¹ H NMR (CDCl₃): δ 7.39-7.28(10H, m), 6.99 (1H, s), 6.61 (1H, s), 5.47 (1H, s), 4.82 (1H, s), 4.67(1H, d, J=12.2 Hz), 4.49 (1H, d, J=12.2 Hz), 4.07 (ABq, 2H), 3.85 (s,3H), 1.20 (3H, s).

EXAMPLE 13 Benzhydryl2β-[[(1-methyl-1H-tetrazol-5-yl)thio]acetoxymethyl]-6-[(Z)-(-butoxycarbonyl)methylene]penicillinate1,1-dioxide (7g)

A mixture of chloride 7b (0.40 g, 0.663 mmol),5-mercapto-1-methyl-1H-tetrazole (93 mg, 0.796 mmol) and NaHCO₃ (67 mg,0.796 mmol) in acetone-water (8 mL, 3:1) was stirred for 6 hours at roomtemperature. The reaction mixture was diluted with CH₂ Cl₂ (50 mL),washed with 5% NaHCO₃ solution (50 mL). The organic layer was dried,concentrated and purified by column chromatography (5% EtOAc/CH₂ Cl₂ aseluent) to give the title compound 7g; 0.29 g, 64%; ¹ H NMR (CDCl₃): δ7.37-7.32 (m, 10H), 6.97 (s, 1H), 6.52 (s, 1H), 5.54 (s, 1H), 4.83 (s,1H), 4.61 (d, J=12.14 Hz, 1H), 4.44 (d, J=12.14 Hz, 1H), 4.21 (d,J=15.67 Hz, 1H), 4.11 (d, J=12.67 Hz, 1H), 3.95 (s, 3H), 1.53 (s, 9H),1.24 (s, 3).

EXAMPLE 14 Benzhydryl2β-[[(1-methyl-1H-tetrazol-5-yl)thio]acetoxymethyl]-6-[(Z)-(methoxycarbonyl)methylene]penicillinate1,1-dioxide (7h)

A mixture of chloride 7f (200 mg, 0.397 mmol),5-mercapto-1-methyl-1H-tetrazole (55 mg, 0.477 mmol) and NaHCO₃ (40 mg,0.477 mmol) in acetone-water (4 mL, 3:1) was stirred for 6 hours at roomtemperature. The reaction mixture was diluted with CH₂ Cl₂ (30 mL),washed with 5% NaHCO₃ solution (30 mL). The organic layer was dried,concentrated and purified by column chromatography (5% EtOAc/CH₂ Cl₂ aseluent) to give the title compound 7h; 0.178 g, 77%; ¹ H NMR (CDCl₃): δ7.36-7.33 (m, 10H), 6.97 (s, 1H), 6.61 (s, 1H), 5.44 (s, 1H), 4.81 (s,1H), 4.66 (d, J=12.12 Hz, 1H), 4.48 (d, J=12.12 Hz, 1H), 4.19 (d,J=16.81 Hz, 1H), 4.09 (d, J=16.81 Hz, 1H), 4.03 (s, 3H), 3.89 (s, 3H),1.25 (s, 3H).

EXAMPLE 15 Disodium salt of2β-(acetoxymethyl)-6-[(Z)-carboxymethylene]-penicillinicacid-1,1-dioxide (8a)

To a solution of benzhydryl2β-(acetoxymethyl)-6-[(Z)-(tert-butoxycarbonyl)methylene]penicillinate-1,1-dioxide,(300 mg, 0.526 mmol, 7a) in anisole (1.7 mL, 15.8 mmol) at 0° C. wasadded trifluoroacetic acid (4.86 mL, 63.26 mmol) over 5 minutes underargon. The reaction mixture was stirred for 20 minutes at 0° C. and for2 minutes at 30° C. Excess TFA was removed in vacuo. The residue wasagain dissolved in EtOAc (10 mL) and treated with aqueous NaHCO₃ (44 mgin 5 mL) and aqueous layer was purified by reverse phrase chromatography(deionized water as eluent) to give the title compound 8a; 160 mg,77.6%; ¹ H NMR (D₂ O): δ 6.53 (1H, s), 5.62 (1H, s), 4.52 (1H, d, J=),4.38 (1H, s), 4.36 (1H, d, J=), 1.98 (3H, s), 1.41 (3H, s).

EXAMPLE 16 Disodium salt of2β-(chloroacetoxymethyl)-6-[(Z)-carboxymethylene]-penicillinate1,1-dioxide (8b)

Sulfone 7b (190 mg, 0.315 mmol) was dissolved in anisole (1.03 mL, 9.45mmol) and cooled in an ice bath. To this solution was addedtrifluoroacetic acid (2.92 mL, 37.84 mmol) and stirring continued for 30minutes at 0° C. Volatiles were removed in vacuo, the residue dissolvedin EtOAc (20 mL) and the solution extracted with NaHCO₃ solution (53 mgin 15 mL of H₂ O). This solution was then placed on a column of CHP20P(Mitsubishi Chemical Corporation) and the disalt 8b eluted withdeionized water; 60 mg, 45%; ¹ H NMR (D₂ O): δ 6.58 (s, 1H), 5.67 (s,1H), 4.69 (d, J=12.36 Hz, 1H), 4.54 (d, J=12.36 Hz, 1H), 4.45 (s, 1H),4.23 (s, 2H), 1.47 (s, 3H).

EXAMPLE 17 Disodium salt of2β-(formyloxymethyl)-6-[(Z)-carboxymethylene]-penicillinate 1,1-dioxide(8c)

Sulfone 7c (310 mg, 0.558 mmol) was dissolved in anisole (1.82 mL, 16.75mmol) and cooled in an ice bath. To this solution was addedtrifluoroacetic acid (5.16 mL, 67.02 mmol) and stirring continued for 30minutes at 0° C. Volatiles were removed in vacuo, the residue dissolvedin EtOAc (30 mL) and the solution extracted with NaHCO₃ solution (94 mgNaHCO₃ in 20 mL of H₂ O). This solution was then placed on a column ofCHP20P (Mitsubishi Chemical Corporation) and the disalt 8c eluted withdeionized water; 100 mg, 47.6%; ¹ H NMR (D₂ O): δ 8.07 (s, 1H), 6.58 (s,1H), 5.68 (s, 1H), 4.68 (d, J=12.31 Hz, 1H), 4.57 (d, J=12.31 Hz, 1H),4.45 (s, 1H), 1.48 (s, 3H).

EXAMPLE 18 Disodium salt of2β-(phenylacetoxymethyl)-6-[(Z)-carboxymethylene]-penicillinate1,1-dioxide (8d)

Sulfone 7d (305 mg, 0.473 mmol) was dissolved in anisole (1.54 mL, 14.2mmol) and cooled in an ice bath. To this solution was addedtrifluoroacetic acid (4.4 mL, 56.74 mmol) and stirring continued for 30minutes at 0° C. Volatiles were removed in vacuo, the residue dissolvedin EtOAc (20 mL) and the solution extracted with NaHCO₃ solution (80 mgNaHCO₃, 0.946 mmol in 15 mL of H₂ O). This solution was then placed on acolumn of CHP20P (Mitsubishi Chemical Corporation) and the disalt 8deluted with deionized water; 85 mg, 37.6%; ¹ H NMR (D₂ O): δ 7.30-7.22(m, 5H), 6.55 (s, 1H), 5.64 (s, 1H), 4.63 (d, J=12.46 Hz, 1H), 4.42 (d,J=12.46 Hz, 1H), 4.39 (s, 1H), 3.69 (s, 2H), 1.48 (s, 3H).

EXAMPLE 19 Sodium salt of2β-(acetoxymethyl)-6-[(Z)-(methoxycarbonyl)methylene]-penicillinic acid1,1 dioxide (8e)

To a solution of benzhydryl2β-(acetoxymethyl)-6-[(Z)-(methoxycarbonyl)-methylene]penicillinate 1,1dioxide, 7e, (270 mg, 0.512 mmol) in anisole (1.7 mL, 15.4 mmol) at 0°C. was added trifluoroacetic acid (4.86 mL, 61.5 mmol) over 5 minutesunder argon. The reaction mixture was stirred for 15 minutes at 0° C.Excess TFA was removed in vacuo. The residue was again dissolved inEtOAc (20 mL) and treated with aqueous NaHCO₃ (5%, 10 mL) and aqueouslayer was purified on a column of CHP20P (Mitsubishi ChemicalCorporation) (deionized water as eluant) to give the title compound 8e;100 mg, 51%; ¹ H NMR (D₂ O): δ 6.68 (s, 1H), 5.79 (s, 1H), 4.57 (d, 1H,J=12.2 Hz), 4.52 (s, 1H), 4.41 (d, 1H, J=12.2 Hz, 1H), 3.74 (s, 3H),2.00 (s, 3H), 1.46 (s, 3H).

EXAMPLE 20 Disodium salt of2β-[[(1-methyl-1H-tetrazol-5-yl)thio]acetoxymethyl]-6-[(Z)-carboxymethylene]penicillinate1,1-dioxide (8g)

Compound 7g (135 mg, 0.197 mmol) was dissolved in anisole (0.65 mL, 5.32mmol) and cooled in an ice bath. To this solution was addedtrifluoroacetic acid (1.83 mL, 23.71 mmol) and stirring was continuedfor 30 minutes at 0° C. Volatiles were removed in vacuo and the residuedissolved in EtOAc (20 mL) and extracted with aqueous NaHCO₃ (33 mgdissolved in 10 mL H₂ O). The aqueous solution was then loaded onto acolumn of CHP20P (Mitsubishi Chemical Corporation) and the disalt 8geluted with deionized water; 43 mg, 43%; ¹ H NMR (D₂ O): δ 6.57 (s, 1H),5.61 (s, 1H), 4.63 (d, J=12.3 Hz, 1H), 4.36 (s, 1H), 3.93-3.87 (m, 5H),1.37 (s, 3H).

EXAMPLE 21 Sodium salt of2β-[[(1-methyl-1H-tetrazol-5-yl)thio]acetoxymethyl]-6-[(Z)-(methoxycarbonyl)methylene]penicillinate1,1-dioxide (8h)

Compound 7h (175 mg, 0.3 mmol) was dissolved in anisole (0.98 mL, 9.0mmol) and cooled in an ice bath. To this solution was addedtrifluoroacetic acid (2.77 mL, 36.02 mmol) and stirring was continuedfor 15 minutes at 0° C. Volatiles were removed in vacuo and the residuedissolved in EtOAc (20 mL) and extracted with aqueous 5% NaHCO₃ (10 mL).The aqueous solution was then loaded onto a column of CHP20P (MitsubishiChemical Corporation) and the salt 8h eluted with 6% EtOH/H₂ O; 69 mg,53%; ¹ H NMR (D₂ O): δ 6.69 (s, 1H), 5.74 (s, 1H), 4.63 (d, J=12.2 Hz,1H), 4.48 (d, J=12.23 Hz, 1H), 4.46 (s, 1H), 3.93 (m, 5H), 3.77 (s, 3H),1.41 (s, 3H).

EXAMPLE 22 Benzhydryl2-(chloromethyl)-6-[(z)-(t-butoxycarbonyl)methylene]-penicillinate (10a)

A solution of 5a (2.5 g, 3.88 mmol) and CuCl2 (0.63 g, 4.66 mmol) in CH₂Cl₂ (60 mL) was stirred for 7 hours at room temperature. The reactionmixture was filtered and filtrate was washed with saturated NaHCO₃ (100mL). The organic layer was dried (Na₂ SO₄), concentrated, and purifiedby column chromatography to give the title compound 10a; 1.43 g, 72%, ¹H NMR (CDCl₃): δ 7.37-7.31 (m, 10H), 6.96 (s, 1H), 6.18 (s, 1H), 6.02(s, 1H), 5.24 (s, 1H), 3.53 (d, J=11.8 Hz, 1H), 3.43 (d, J=11.8 Hz, 1H),1.51 (s, 9H), 1.34 (s, 3H).

EXAMPLE 23 Benzhydryl2β-(chloromethyl)-6-[(Z)-(methoxycarbonyl)methylene]-penicillinate (10b)

A solution of 5b (0.8 g, 1.33 mmol) and CuCl2 (0.214 g, 1.59 mmol) inCH₂ Cl₂ (20 mL) was stirred for 7 hours at room temperature. Thereaction mixture was filtered and filtrate was washed with saturatedNaHCO₃ (20 mL). The organic layer was dried (Na₂ SO₄), concentrated, andpurified by column chromatography to give the title compound 10b; 0.42g, 75%; ¹ H NMR (CDCl₃): δ 7.39-7.35 (m, 10H), 6.96 (s, 1H), 6.31 (s,1H), 6.05 (s, 1H), 5.23 (s, 1H), 3.81 (s, 3H), 3.55 (d, J=12.3 Hz, 1H),3.41 (d, J=12.3 Hz, 1H), 1.32 (s, 3H).

EXAMPLE 24 Benzhydryl2β-(chloromethyl)-6-[(Z)-(t-butoxycarbonyl)methylene]penicillinate1,1-dioxide (11a)

To a solution of sulfide 10a, (400 mg, 0.78 mmol) in CH₂ Cl₂ (20 mL) andpH 6.4 phosphate buffer solution (20 mL) was added mCPBA (70%, 424 mg,1.72 mmol). The mixture was stirred at room temperature for 18 hours,and then diluted with CH₂ Cl₂ (10 mL). The organic layer was washed withNaHCO₃ solution (20 mL), dried (Na₂ SO₄), concentrated and purified bycolumn chromatography to give the title compound 11a; 360 mg, 86%; ¹ HNMR (CDCl₃): δ 7.38-7.33 (10H, m), 6.99 (1H, s), 6.53 (1H, s), 5.65 (1H,s), 4.69 (1H, s), 4.23 (1H, d, J=12.1 Hz), 3.96 (1H, d, J=12.1 Hz), 1.51(9H, s), 1.09 (3H, s)

EXAMPLE 25 Benzhydryl2β-(chloromethyl)-6-[(Z)-(methoxycarbonyl)methylene]penicillinate1,1-dioxide (11b)

To a solution of sulfide 10b, (300 mg, 0.73 mmol) in CH₂ Cl₂ (15 mL) andpH 6.4 phosphate buffer solution (15 mL) was added mCPBA (70%, 395 mg,1.6 mmol). The mixture was stirred at room temperature for 1 8 hours,and then diluted with CH₂ Cl₂ (10 mL). The organic layer was washed withNaHCO₃ solution (20 mL), dried (Na₂ SO₄), concentrated and purified bycolumn chromatography to give the title compound 11b; 240 mg, 74%; ¹ HNMR (CDCl₃): δ 7.38-7.33 (10H, m), 6.98 (1H, s), 6.61 (1H, s), 5.49 (1H,s), 4.87 (1H, s), 3.97 (1H, d, J=12.3 Hz), 3.86 (s, 3H), 3.80 (1H, d,J=12.3 Hz), 1.32 (3H, s).

EXAMPLE 26 Disodium salt of2β-(chloromethyl)-6-[(Z)-carboxymethylene]penicillinate 1,1-dioxide(12c)

To a solution of sulfone 11a, (300 mg, 0.55 mmol) in anisole (1.8 mL,16.5 mmol) at 0° C. was added trifluoroacetic acid (5.1 mL, 66.0 mmol)over 5 minutes under argon. The reaction mixture was stirred for 10minutes at 0° C. Excess TFA and anisole were removed in vacuo. Theresidue was again dissolved in EtOAc (25 mL) and treated with aqueousNaHCO₃ (70 mg solid, 0.825 mmol, dissolved in 10 mL H₂ O) and aqueouslayer was purified on a column of CHP20P (Mitsubishi ChemicalCorporation) (deionized water as eluent) to give the title compound 12c;65 mg; ¹ H NMR (D₂ O): δ 6.54 (1H, s), 5.87 (1H, s), 4.31 (1H, s), 4.05(2H, ABq, J=12.1 Hz), 1.39 (3H, s).

EXAMPLE 27 Sodium salt of2β-(chloromethyl)-6-[(Z)-(t-butoxycarbonyl)methylene]-penicillinic acid1,1 dioxide (12a)

The column described in Example 26 was further eluted (7% EtOH in water)to give the title compound 12a; 50 mg; ¹ H NMR (D₂ O): δ 6.54 (1H, s),6.02 (1H, s), 4.39 (1H, s), 4.08 (2H, ABq, J=12.1 Hz), 1.47 (9H, s),1.41 (3H, s).

EXAMPLE 28 Sodium salt of2β-(chloromethyl)-6-[(Z)-(methoxycarbonyl)methylene]-penicillanic acid1,1 dioxide (12b)

To a solution of sulfone 11b, (280 mg, 0.629 mmol) in anisole (2.1 mL,18.9 mmol) at 0° C. was added trifluoroacetic acid (5.82 mL, 75.5 mmol)over 5 minutes under argon. The reaction mixture was stirred for 15minutes at 0° C. Excess TFA and anisole were removed in vacuo. Theresidue was again dissolved in EtOAc (20 mL) and treated with aqueousNaHCO₃ (5%, 20 mL) and aqueous layer was purified on a column of CHP20P(Mitsubishi Chemical Corporation) (4% EtOH in deionized water as eluent)to give the title compound 12b; 123 mg, 62%; ¹ H NMR (D₂ O): δ 6.72 (1H,s), 5.84 (1H, s), 4.45 (1H, s), 4.19 (1H, d, J=12.4 Hz), 4.08 (1H, d,J=12.4 Hz, 1H), 3.76 (3H, s), 1.60 (3H, s).

EXAMPLE 29 Benzhydryl2β-(hydroxymethyl)-6-[(Z)-(t-butoxycarbonyl)methylene]penicillinate (13)

Chloroacetate 6b (1.9 g, 3.33 mmol) was dissolved in DMF (4 mL) andcooled to 0° C. Pyridine (1.47 mL, 18.3 mmol) was added. Thiourea (0.76g, 9.99 mmol) was added to the solution and it was stirred at 0°C. untilall the thiourea was dissolved. The ice bath was then removed and thereaction allowed to reach room temperature. The volatiles were thenremoved in vacuo and the residue dissolved in EtOAc (30 mL). Thissolution was then washed with water (50 mL), dried (Na₂ SO₄), andconcentrated to produce alcohol 13 (1.48 g, 90%) which was used inExample 30 without further purification; ¹ H NMR (CDCl₃): δ 87.39-7.29(m, 10H), 6.95 (s, 1H), 6.16 (s, 1H), 5.99 (s, 1H), 4.99 (s, 1H), 3.49(d, J=11.6 Hz, 1H), 3.40 (d, J=11.6 Hz, 1H), 1.49 (s, 9H), 1.26 (s, 3H).

EXAMPLE 30 Benzhydryl2β-(formyl)-6-[(Z)-(t-butoxycarbonyl)methylene]penicillinate (14)

A solution of oxalyl chloride (0.264 mL, 3.03 mmol) in CH₂ Cl₂ (16 mL)was cooled to -78° C. and anhydrous DMSO (0.267 mL 3.43 mmol) was addeddropwise. the solution was stirred at -78° C. for 15 minutes, then asolution of alcohol 13 in CH₂ Cl₂ (5 mL) was added dropwise. Thereaction mixture was stirred for 3 hours at -78° C. and thentriethylamine (0.983 mL, 7.07 mmol) was added. The reaction mixture wasallowed to reach -10° C. The reaction was then quenched with 1N HCl (0.5mL) and the organic layer was washed with water (30 mL), dried (Na₂SO₄), and concentrated to produce aldehyde 14 in quantitative yieldwhich was used in Example 31 without further purification; ¹ H NMR(CDCl₃): δ 9.09 (s, 1H), 7.38-7.31 (m, 10H), 6.97 (s, 1H), 6.14 (s, 1H),6.02 (s, 1H), 5.41 (s, 1H), 1.51 (s, 9H), 1.27 (s, 3H).

EXAMPLE 31 Benzhydryl2β-[(E/Z)-(cyanoethenyl)]-6-[(Z)-(t-butoxycarbonyl)methylene]penicillinate(15)

A solution of aldehyde 14 (1 g, 2.03 mmol) in acetonitrile (10 mL) wasadded dropwise at -20° C. to a suspension ofcyanomethylenetriphenylphosphorane (0.61 g, 2.03 mmol) and 0.4 M LiClO₄in acetonitrile (10 mL). After 4 hours, the solvent was evaporated andthe residue dissolved in EtOAc (50 mL). The organic layer was washedwith water (50 mL), dried (Na₂ SO₄), concentrated and purified by columnchromatography to give the title compound 15; 0.41 g, 40%; ¹ H NMR(CDCl₃): (major Z isomer) δ 7.41-7.38 (m, 10H), 6.99 (s, 1H), 6.48 (d,J=11.9 Hz, 1H), 6.23 (s, 1H), 6.09 (s, 1H), 5.39 (d, J=11.9 Hz, 1H),4.99 (s, 1H), 1.54 (s, 3H), 1.53 (s, 9H).

EXAMPLE 32 Benzhydryl2β-[(E/Z)-(cyanoethenyl)]-6-[(Z)-(t-butoxycarbonyl)methylene]penicillin-ate1,1-dioxide (16)

To a solution of sulfide 15 (0.35 g, 0.678 mmol) in CH₂ Cl₂ (10 mL) wasadded mCPBA (70%, 0.37 g, 1.49 mmol) in one portion followed by pH 6.4phosphate buffer solution (10 mL) and the reaction mixture was stirredovernight. The organic layer was separated, washed with saturatedaqueous NaHCO₃ (1×20 mL), dried (Na₂ SO₄), concentrated and purified bysilica gel chromatography to give the title compound 16; 0.240 g, 65%; ¹H NMR (CDCl₃): (major isomer) δ 7.38-7.27 (10H, m), 6.98 (1H, s), 6.59(1H, s), 6.43 (d, J=16.4 Hz, 1H), 5.53 (s, 1H), 5.35 (d, J=16.4 Hz, 1H),4.67 (s, 1H), 1.52 (s, 9H), 1.51 (s, 3H).

EXAMPLE 33 Disodium Salt of2β-[(E/Z)-(cyanoethenyl)]-6-[(Z)-carboxymethylene]-penicillinate1,1-dioxide (17)

To a solution of sulfone 16, (240 mg, 0.438 mmol) in anisole (1.43 mL,13.1 mmol) at 0° C. was added trifluoroacetic acid (4.1 mL, 53.5 mmol)over 5 minutes under argon. The reaction mixture was stirred for 30minutes at 0° C. Excess TFA and anisole were removed in vacuo. Theresidue was again dissolved in EtOAc (20 mL) and treated with aqueousNaHCO₃ (67 mg solid, 0.79 mmol, dissolved in 10 mL H₂ O) and aqueouslayer was purified on a column of CHP20P (Mitsubishi ChemicalCorporation) to give the title compound 17; 60 mg, 37%; ¹ H NMR (D₂ O):δ 6.73 (d, J=16.3 Hz, 1H), 6.42 (1H, s), 5.73 (d, J=16.3 Hz, 1H), 5.54(1H, s), 4.16 (1H, s), 1.47 (3H, s).

EXAMPLE 34 Benzhydryl2β-{[3',4'-di-(4-methoxybenzyloxy)phenyl]acetoxy}-methyl-6-[(Z)-(t-butoxycarbonyl)methylene]penicillinate(6i)

Using a procedure similar to that described in Example 6, exceptreplacing the disulfide 5b and the chloroacetic acid used therein withdisulfide 5a and 3,4-di(4-methoxybenzyloxy)phenylacetic acid, the titlecompound was prepared; ¹ H NMR (CDCl₃) δ=7.25-7.36 (m, 15H), 6.48-6.90(m, 7H), 6.17 (s, 1H), 6.00 (s, 1H), 5.04 (s, 2H), 4.99 (s, 2H), 4.61(s, 1H), 4.02 (d, J=8.24 Hz, 1H) 3.81 (s, 3H), 3.77 (s, 3H), 3.78 (d,J=8.24 Hz, 1H), 3.55 (s, 2H1), 1.52 (s, 9H), 1.48 (s, 3H).

EXAMPLE 35 Benzhydryl2β-[3',4'-di-(4-methoxybenizyloxy)phenyl]acetoxy-methyl-6-[(Z)-(t-butoxycarbonyl)methylene]-1,1-dioxopenicillinate(7i)

Using a procedure similar to that described in Example 12, exceptreplacing the compound 6f used therein with the compound 6i, the titlecompound was prepared; 1H NMR (CDCl₃) δ=7.26-7.36 (m, 15H), 6.85-6.89(m, 8H), 6.48 (s, 1H), 5.46 (s, 1H), 5.03 (s, 4H), 4.78 (s, 1H), 4.54(d, J=6.98 Hz, 1H), 4.37 (d, J=6.98 Hz, 1H), 3.80 (s, 6H), 3.53 (s, 2H),1.55 (s, 3H), 1.53 (s, 9H).

EXAMPLE 36 Disodium Salt of2β-[(3',4'-Dihydroxyphenyl)acetoxy]methyl-6-[(Z)-carboxymethylene]-1,1-dioxopenicillinate(8i)

Using a procedure similar to that described in Example 21, exceptreplacing the compound 7h used therein with compound 7i, the titlecompound was prepared; 1H NMR (CDCl₃) δ=6.53-6.77 (m, 4H), 5.77 (s, 1H),4.41 (d, J=8.24 Hz, 1H), 3.54 (s, 2H), 1.40 (s, 3H).

EXAMPLE 37 Sodium2β-(acetoxymethyl)-1,1-dioxo-6-[(Z)-2'-pyridylmethylene]penicillinate(29a)

A solution of benzyl ester 28a (330 mg, 0.702 mmol) and LiI (376 mg,2.81 mmol) in EtOAc (15 mL) was heated to reflux for 12 hours. Thereaction mixture was cooled to room temperature, diluted with EtOAc (25mL) and extracted with 5% NaHCO₃ solution (20 mL). The aqueous layer wasloaded onto a column of CHP20P (Mitsubishi Chemical Corporation) andcompound 29a (123 mg, 44%) was eluted with 5-10% EtOH-H₂ O; ¹ H NMR (D₂O): δ 8.57 (d, J=4.5 Hz, 1H), 7.81 (m, 1H), 7.52 (d, J=7.69 Hz, 1H),7.42 (s, 1H), 7.37 (m, 1H), 5.98 (s, 1H), 4.60 (d, J=12.3 Hz, 1H), 4.45(m, 2H), 2.04 (s, 3H), 1.51 (s, 3H).

The intermediate compound 28a was prepared as follows.

a.4-(2'-Benzothiazolyldithio)-3-[(allyloxycarbonyl)amino]-1-[1'-benzyloxycarbonyl-2'-methylprop-2'-enyl]azetidin-2-one(22a).

A solution of sulfoxide 21a (48 g, 0.118 mol) and 2-mercaptothiazole(19.8 g, 0.118 mol) in toluene (1.5 L) was heated to reflux for 3.5hours. Toluene was removed under reduced pressure to obtain thedisulfide 22a in quantitative yield; ¹ H NMR (CDCl₃) δ=7.72 (1H, d,J=8.1 Hz), 7.58 (1H, d, J=8.1 Hz), 7.69-7.25 (7H, m), 6.09 (1H, bd,J=10.7 Hz), 5.65 (1H, m), 5.35 (1H, d, J=4.4 Hz), 5.14-4.94 (4H, m),4.85 (1H, s), 4.77 (1H, s), 4.41 (2H, m), 1.89 (3H, s).

b. Benzyl 2β-(acetoxymethyl)-6-[(allyloxycarbonyl)amino]penicillinate(23a).

A mixture of disulfide 22a (9.0 g, 16.2 mmol), acetic acid (40 mL, 697.3mmol), and silver acetate (5.6 g, 33.7 mmol) in CH₂ Cl₂ (350 mL) wasstirred for 4 hours at room temperature. The reaction mixture wasfiltered and the filtrate washed with 10% NaHCO₃ solution (500 mL). Theorganic layer was dried over Na₂ SO₄, concentrated, and purified bysilica gel chromatography to yield a 4:1 mixture of cepham 24a and penam23a (yield 6.4 g, 88.3%); ¹ H NMR (CDCl₃): δ 7.37 (bs, 5H), 5.92 (m,2H), 5.61 (d, J=4.16 Hz, 1H), 5.43 (m, 1H), 5.35-5.17 (m, 4H), 4.69 (s,1H), 4.61 (bd, 2H), 4.37 (d, J=11.6 Hz, 1H), 3.80 (d, J=11.6 Hz, 1H),2.11 (s, 3H), 1.41 (s, 3H).

c. Benzyl 2β-(acetoxymethyl)-6-aminopenicillinate (25a).

To a solution of carbamate 23a (6.0 g, 13.42 mmol), acetic acid (1.8 mL,32.2 mmol), and Pd(PPh₃)₄ (310 mg, 0.268 mmol) in CH₂ Cl₂ (600 mL) wasadded tributyltin hydride (3.98 mL, 14.8 mmol) and the reaction wasstirred for 30 minutes at room temperature. The reaction mixture waswashed with NaHCO₃ solution (200 mL) and dried over Na₂ SO₄.Purification by silica gel chromatography yielded amine 25a (3.25 g,66.7%); ¹ H NMR (CDCl₃): δ 7.37-7.32 (m, 5H), 5.55 (d, J=4.20 Hz, 1H),5.19 (m, 2H), 4.70 (s, 1H), 4.53 (d, J=4.20 Hz, 1H), 4.23 (d, J=11.5 Hz,1H), 3.87 (d, J=11.5 Hz, 1H), 2.06 (s, 3H), 1.35 (s, 3H).

d. Benzyl 2β-(acetoxymethyl)-6-oxopenicillinate (26a).

To a solution of amine 25a (2.2 g, 6.06 mmol) in EtOAc (50 mL) was addedisopropyl nitrite (2.03 mL, 9.09 mmol, 40% solution in CH₂ Cl₂) followedby trifluoroacetic acid (0.014 mL, 0.18 mmol). The reaction mixture wasstirred for 30 minutes at room temperature. Volatiles were removed invacuo and the yellow solid was dissolved in C₆ H₆ (10 mL). To thissolution was added propylene oxide (20 mL) followed by Rh₂ (OOct)₄ (15mg) and the reaction mixture was stirred for 20 minutes at roomtemperature. Volatiles were removed to obtain the ketone 26a (2.2 g,quantitative); ¹ H NMR (CDCl₃): δ 7.39-7.36 (m, 5H), 5.77 (s, 1H), 5.22(s, 2H), 5.02 (s, 1H), 4.09 (d, J=11.9 Hz, 1H), 3.84 (d, J=11.9 Hz, 1H),2.07 (s, 3H), 1.37 (s, 3H).

e. Benzyl 2β-(acetoxymethyl)-6-[(Z)-2'-pyridylmetlhylene]penicillinate(27a).

To a suspension of triphenyl(2-pyridylmethyl)phosphonium chloride (3.55g, 9.12 mmol) in dry THF (30 mL) was added NaNH₂ (0.31 g, 7.9 mmol) andthe reaction mixture was stirred for 1 hour at room temperature. Thesolution was then allowed to stand motionless (in order to allow theprecipitate to settle) for 2 hours. A second solution of ketone 26a (2.2g, 6.1 mmol) in dry THF (20 mL) was chilled to -78° C. To this ketonesolution was carefully added the supernatant solution of the Wittigylide at -78° C. and the reaction mixture stirred for 40 minutes at thesame temperature. The reaction mixture was then quenched with sat NH₄ Clsolution (50 mL) and extacted with CH₂ Cl₂ (100 mL). The organic layerwas dried, concentrated, and purified by silica gel chromatography toproduce 27a (1.49 g, 56%); ¹ H NMR (CDC₃): δ 8.62 (d, J=4.27 Hz, 1H),7.69 (m, 1H), 7.42-7.33 (m, 5H), 6.92 (s, 1H), 6.27 (s, 1H), 5.23 (s,2H), 4.93 (s, 1H), 4.10 (d, J=11.8 Hz, 1H), 3.83 (d, J=11.8 Hz, 1H),2.07 (s, 3H), 1.27 (s, 3H).

f. Benzyl2β-(acetoxymethyl)-1,1-dioxo-6-[(Z)-2'-pyridylmiethylene]-penicillinate(28a).

To a solution of sulfide 27a (1.1 g, 2.51 mmol) in CH₂ Cl₂ (30 mL) wasadded mCPBA (70%, 1.37 g, 5.53 mmol) followed by pH 6.4 phosphate buffersolution (30 mL) and the reaction mixture was stirred overnight at roomtemperature. The organic layer was separated, washed with 5% NaHCO₃solution (50 mL), dried, concentrated and purified by columnchromatography to yield the sulfone 28a (0.78 66.1%); ¹ H NMR (CDCl₃): δ8.68 (d, J=4.28 Hz, 1H), 7.72 (m, 1H), 7.37 (m, 5H), 7.30 (m, 1H), 7.26(s, 1H), 5.76 (s, 1H), 5.29 (d, J=11.9 Hz, 1H), 5.23 (d, J=11.9 Hz, 1H),4.69 (s, 1H), 4.57 (d, J=12.0 Hz, 1H), 4.39 (d, J=12.0 Hz, 1H), 2.06 (s,3H), 1.39 (s, 3H).

The intermediate compounds 20a and 21a (FIG. 8) can be prepared asdescribed by Butynak et. al. J. Am. Chem. Soc. 120, 6846-6847 (1998).

EXAMPLE 38 Sodium1,1-Dioxo-2β-(phenylacetoxy)methyl-6-[(Z)-2'-pyridylmethylene]penicilliniate(29b)

A solution of benzhydryl ester 28b (590 mg, 1.08 mmol) was dissolved inanisole (3.5 mL, 32.4 mmol) and cooled to 0° C. To this solution wasadded TFA (10 mL, 129.6 mmol) at 0° C. and the reaction was stirred for20 minutes at the same temperature. Volatiles were removed in vacuo, andthe residue was dissolved in ethyl acetate (30 mL) and extracted with10% NaHCO₃ solution (20 mL). The aqueous layer was loaded onto a columnof CHP20P (Mitsubishi Chemical Corporation) and compound 29b (298 mg,69%) was eluted with 5-10% EtOH-H₂ O; ¹ H NMR (D₂ O): δ 8.53 (d, J=4.5Hz, 1H), 7.77 (m, 1H), 7.47 (d, J=7.72 Hz, 1H), 7.33 (m, 2H), 7.24-7.17(m, 5H), 5.89 (s, 1H), 4.60 (d, J=12.6 Hz 1H), 4.41 (d, J=12.6 Hz, 1H),4.38 (s, 1H), 3.65 (s, 2H), 1.39 (s, 3H).

The intermediate compound 28b was prepared as follows.

a.4-(2'-Benzothiazolyldithio)-3-[(allyloxycarbonyl)amino]-1-[1'-benzhydryloxycarbonyl-2'-methylprop-2'-enyl]azetidin-2-one(22b).

To a solution of benzhydryl 6-[(allyloxycarbonyl)amido]penicillinatesulfoxide, 21b, (26.0 g, 53.9 mmol) in toluene (800 mL) was added2-mercaptobenzothiazole (19.8 g, 53.9 mmol) and the reaction was heatedto reflux for 3.5 hours. Volatiles were removed under reduced pressureto give 22b (quantitative yield); ¹ H NMR (CDCl₃): δ 7.85 (1H, d, J=8.1Hz), 7.72 (1H, d, J=8.1 Hz), 7.50-7.10 (12H, m), 6.90 (1H, s), 6.15 (1H,bd, J=10.5 Hz), 5.85 (1H, m), 5.50 (1H, d, J=4.4 Hz), 5.35-5.17 (3H m),5.12 (1H, s), 5.02 (1H, s), 4.95 (1H, s), 4.55 (2H, m), 1.89 (3H, s).

b. Benzhydryl2-(phenylacetoxy)methyl-6-[(allyloxycarbonyl)amino]penicillinate (23b).

A mixture of disulfide 22b (6.3 g, 9.99 mmol), phenylacetic acid (58.4g, 429.3 mmol) and silver acetate (3.47 g, 20.8 mmol) in CH₂ Cl₂ (180mL) was stirred at room temperature for 4 hours. The reaction mixturewas filtered and the filtrate was washed with 10% NaHCO₃ solution (500mL). The organic layer was dried over Na₂ sO₄, concentrated and purifiedby silica gel chromatography to yield a 4:1 mixture of penam 23b andcepham 24b (yield 4.5 g, 75%); ¹ H NMR (CDCl₃): δ 7.44-7.26 (m, 15H),6.93 (s, 1H), 5.95 (m, 1H), 5.87 (bd, 1H), 5.60 (d, J=4.8 Hz, 1H), 5.51(m, 1H), 5.35 -5.23 (m, 2H), 4.71 (s, 1H), 4.61 (bd, 2H), 4.34 (d,J=11.6 Hz, 1H), 3.83 (d, J=11.8 Hz, 1H), 2.16 (s, 3H), 1.19 (s, 3H).

c. Benzhydryl 2β-(phenylacetoxy)methyl-6-aminopenicillinate (25b).

To a solution of carbamate 23b (4.5 g, 7.5 mmol), acetic acid (1.02 mL,17.98 mmol) and Pd(Ph₃ P)₄ (172 mg, 1.5 mmol) in CH₂ Cl₂ (450 mL) wasadded (n-Bu)₃ SnH (2.21 mL, 8.24 mmol) and the reaction was stirred for30 minutes at room temperature. The reaction mixture was washed withNaHCO₃ solution (200 mL), and the organic layer was dried, concentrated,and purified by silica gel chromatography to give amine 25b (2.3 g,70%); ¹ H NMR (CDCl₃): δ 7.36-7.24 (m, 15H, 6.93 (s, 1H), 5.56 (d,J=4.24 Hz, 1H), 4.75 (s, 1H), 4.53 (d, J=4.24 Hz, 1H), 4.26 (d, J=11.5Hz, 1H), 4.00 (d, J=11.5 Hz, 1H), 3.68 (q, 2H), 1.18 (s, 3H).

d. Benzhydryl 2β-(phenylacetoxy)methyl-6-oxopenicillinate (26b).

To a solution of amine 25b (2.0 g, 4.45 mmol) in EtOAc (40 mL) was addedisopropyl nitrite (1.52 mL, 6.83 mmol, 40% solution in CH₂ l ₂) followedby trifluoroacetic acid (0.010 mL, 0.14 mmol). The reaction mixture wasstirred for 30 minutes at room temperature. Volatiles were removed invacuo and the yellow solid was dissolved in benzene (10 mL). To thissolution was added propylene oxide (20 mL) followed by Rh₂ (OOct)₄ (15mg) and the reaction mixture was stirred for 20 minutes at roomtemperature. Volatiles were removed to obtain the ketone 26b (2.0 g,quantitative); ¹ H NMR (CDCl₃): δ 7.39-7.27 (m, 15H 1H), 6.97 (s, 1H),5.81 (s, 1H), 5.08 (s, 1H), 4.14 (d, J=11.9 Hz, 1H), 3.80 (d, J=11.9 Hz,1H), 3.64 (q, 2H), (s, 3H).

e. Benzhydryl2β-(phenylacetoxy)methyl-6-[(Z)-2'-pyridylmethylene]penicillinate (27b).

To a suspension of triphenyl(2-pyridylmethyl)phosphonium chloride (2.67g, 6.84 mmol) in dry THF (20 mL) was added NaNH₂ (0.23 g, 5.94 mmol) andthe reaction mixture was stirred for 1 hour at room temperature. Thesolution was then allowed to stand motionless (in order to allow theprecipitate to settle) for 2 hours. A second solution of ketone 26b (2.0g, 4.57 mmol) in dry THF (20 mL) was chilled to -78° C. To this ketonesolution was carefully added the supernatant solution of the Wittigylide at -78° C. and the reaction mixture stirred for 40 minutes at thesame temperature. The reaction mixture was then quenched with sat NH₄ Clsolution (50 mL) and extacted with CH₂ Cl₂ (100 mL). The organic layerwas dried, concentrated, and purified by silica gel chromatography toproduce 27b (760 mg, 32%); ¹ H NMR (CDCl₃): δ 8.64 (d, J=4.18 Hz, 1H),7.70 (m, 1H), 7.40-7.21 (m, 17H), 6.97 (s, 1H), 6.94 (s, 1H), 6.28 (s,1H), 4.97 (s, 1H), 4.12 (d, J=11.8 Hz, 1H), 3.82 (d, J=11.8 Hz, 1H),3.66 (q, 2H), 1.23 (s, 3H).

f. Benzhydryl1,1-dioxo-2β-(phenylacetoxy)methyl-6-[(Z)-2'-pyridylmethylene]penicillinate(28b).

To a solution of sulfide 27b (0.7 g, 1.36 mmol) in CH₂ Cl₂ (30 mL) wasadded mCPBA (70%, 0.71 g, 2.86 mmol) followed by pH 6.4 phosphate buffersolution (30 mL) and the reaction mixture was stirred overnight at roomtemperature. The organic layer was separated, washed with 5% NaHCO₃solution (50 mL), dried, concentrated and purified by columnchromatography to yield the sulfone 28b (0.595 g, 80 %); ¹ H NMR(CDCl₃): δ 8.70 (d, J=3.76 Hz, 1H), 7.73 (m, 1H), 7.36-7.26 (m, 17H),6.97 (s, 1H), 5.75 (s, 1H), 4.73 (s, 1H), 4.63 (d, J=12.3 Hz, 1H), 4.40(d, J=12.3 Hz, 1H), 3.65 (s, 2H), 1.15 (s, 3H).

The intermediate compounds 20b and 21b (FIG. 8) can be prepared asdescribed by Buynak et. al. J. Am. Chem. Soc. 120, 6846-6847 (1998).

EXAMPLE 39

The following illustrate representative pharmaceutical dosage forms,containing a compound of formula I (`Compound X`), for therapeutic orprophylactic use in humans.

    ______________________________________                                        (i) Tablet 1         mg/tablet                                                ______________________________________                                          `Compound X` 100.0                                                            Lactose 77.5                                                                  Povidone 15.0                                                                 Croscarmellose sodium 12.0                                                    Microcrystalline cellulose 92.5                                               Magnesium stearate 3.0                                                         300.0                                                                      ______________________________________                                          (ii) Tablet 2 mg/tablet                                                     ______________________________________                                          `Compound X` 20.0                                                             Microcrystalline cellulose 410.0                                              Starch 50.0                                                                   Sodium starch glycolate 15.0                                                  Magnesium stearate 5.0                                                         500.0                                                                      ______________________________________                                          (iii) Capsule mg/capsule                                                    ______________________________________                                          `Compound X` 10.0                                                             Colloidal silicon dioxide 1.5                                                 Lactose 465.5                                                                 Pregelatinized starch 120.0                                                   Magnesium stearate 3.0                                                         600.0                                                                      ______________________________________                                          (iv) Injection 1 (1 mg/ml) mg/ml                                            ______________________________________                                          `Compound X` (free acid form) 1.0                                             Dibasic sodium phosphate 12.0                                                 Monobasic sodium phosphate 0.7                                                Sodium chloride 4.5                                                           1.0 N Sodium hydroxide solution q.s.                                          (pH adjustment to 7.0-7.5)                                                    Water for injection q.s. ad 1 mL                                            ______________________________________                                          (v) Injection 2 (10 mg/ml) mg/ml                                            ______________________________________                                          `Compound X` (free acid form) 10.0                                            Monobasic sodium phosphate 0.3                                                Dibasic sodium phosphate 1.1                                                  Polyethylene glycol 400 200.0                                                 01 N Sodium hydroxide solution q.s.                                           (pH adjustment to 7.0-7.5)                                                    Water for injection q.s. ad 1 mL                                            ______________________________________                                          (vi) Aerosol mg/can                                                         ______________________________________                                          `Compound X` 20.0                                                             Oleic acid 10.0                                                               Trichloromonofluoromethane 5,000.0                                            Dichlorodifluoromethane 10,000.0                                              Dichlorotetrafluoroethane 5,000.0                                           ______________________________________                                          (vii) Tablet mg/tablet                                                      ______________________________________                                          `Compound X` 100.0                                                            β-lactam antibiotic 100.0                                                Lactose 77.5                                                                  Povidone 15.0                                                                 Croscarmellose sodium 12.0                                                    Microcrystalline cellulose 92.5                                               Magnesium stearate 3.0                                                         400.0                                                                      ______________________________________                                          (viii) Tablet mg/tablet                                                     ______________________________________                                          `Compound X` 20.0                                                             β-lactam antibiotic 10.0                                                 Microcrystalline cellulose 410.0                                              Starch 50.0                                                                   Sodium starch glycolate 15.0                                                  Magnesium stearate 5.0                                                         510.0                                                                      ______________________________________                                          (ix) Capsule mg/capsule                                                     ______________________________________                                          `Compound X` 10.0                                                             β-lactam antibiotic 10.0                                                 Colloidal silicon dioxide 1.5                                                 Lactose 465.5                                                                 Pregelatinized starch 120.0                                                   Magnesium stearate 3.0                                                         610.0                                                                      ______________________________________                                          (x) Injection 1 (1 mg/ml) mg/ml                                             ______________________________________                                          `Compound X` (free acid form) 1.0                                             β-lactam antibiotic 1.0                                                  Dibasic sodium phosphate 12.0                                                 Monobasic sodium phosphate 0.7                                                Sodium chloride 4.5                                                           1.0 N Sodium hydroxide solution q.s.                                          (pH adjustment to 7.0-7.5)                                                    Water for injection q.s. ad 1 mL                                            ______________________________________                                    

The above formulations may be obtained by conventional procedures wellknown in the pharmaceutical art. The β-lactam antibiotic in the aboveformulations can be any β-lactam antibiotic, including those identifiedspecifically hereinabove.

All publications, patents, and patent documents are incorporated byreference herein, as though individually incorporated by reference. Theinvention has been described with reference to various specific andpreferred embodiments and techniques. However, it should be understoodthat many variations and modifications may be made while remainingwithin the spirit and scope of the invention.

What is claimed is:
 1. A compound of formula (I): ##STR3## wherein R¹and R² are each independently hydrogen, (C₁ -C₁₀)alkyl, (C₃-C₈)cycloalkyl, (C₂ -C₁₀)alkenyl, (C₂ -C₁₀)alkynyl, --COOR_(a),--CONR_(b) R_(c), cyano, --C(═O)R_(d), --OR_(e), aryl, heteroaryl,oxazolidinyl, isoxazolidinyl, morpholinyl, --S(O)_(m) R_(f), --NR_(g)R_(h), azido, or halo;R³ is (C₃ -C₁₀)alkyl, (C₂ -C₁₀)alkenyl, (C₂-C₁₀)alkynyl, (C₁ -C₁₀)alkanoyl, (C₃ -C₈)cycloalkyl, aryl, heteroaryl,aryl(C₁ -C₁₀)alkyl, heteroaryl(C₁ -C₁₀)alkyl, or --CH₂ R_(i), whereinR_(i) is halo, cyano, cyanato, --OR_(j), --NR_(k) R_(l), azido,--SR_(m), or (C₃ -C₈)cycloalkyl; R⁴ is hydrogen, (C₁ -C₁₀)alkyl, (C₃-C₈)cycloalkyl, (C₂ -C₁₀)alkenyl, (C₂ -C₁₀)alkynyl, aryl, or heteroaryl;m and n are each independently 0, 1, or 2; each R_(a) -R_(f) isindependently hydrogen, (C₁ -C₁₀)alkyl, (C₃ -C₈)cycloalkyl, (C₂-C₁₀)alkenyl, (C₂ -C₁₀)alkynyl, aryl, heteroaryl, oxazolidinyl,isoxazolidinyl, or morpholinyl; each R_(g) or R_(h) is independentlyhydrogen, (C₁ -C₁₀)alkyl, (C₃ -C₈)cycloalkyl, (C₂ -C₁₀)alkenyl, (C₂-C₁₀)alkynyl, (C₁ -C₁₀)alkanoyl, aryl, benzyl, phenethyl, heteroaryloxazolidinyl, isoxazolidinyl, or morpholinyl; or R_(g) and R_(h)together with the nitrogen to which they are attached are triazolyl,imidazolyl, oxazolidinyl, isoxazolidinyl, pyrrolyl, morpholino,piperidino, pyrrolidino, pyrazolyl, indolyl, or tetrazolyl; R_(j) ishydrogen, (C₁ -C₁₀)alkyl, (C₃ -C₈)cycloalkyl, (C₂ -C₁₀)alkenyl, (C₂-C₁₀)alkynyl, --C(═O)N(RP)₂, aryl, heteroaryl, arylcarbonyl,heteroarylcarbonyl, or (C₁ -C₁₀)alkanoyl, wherein each R_(p) isindependently hydrogen, (C₁ -C₁₀)alkyl, aryl, benzyl, phenethyl, orheteroaryl; each R_(k) or R_(l) is independently hydrogen, (C₁-C₁₀)alkyl, (C₃ -C₈)cycloalkyl, (C₂ -C₁₀)alkenyl, (C₂ -C₁₀)alkynyl, (C₁-C₁₀)alkanoyl, --C(═O)N(R_(q))₂, aryl, benzyl, phenethyl, heteroaryloxazolidinyl, isoxazolidinyl, or morpholinyl, wherein each R_(q) isindependently hydrogen, (C₁ -C₁₀)alkyl, aryl, benzyl, phenethyl, orheteroaryl; or R_(k) and R_(l) together with the nitrogen to which theyare attached are triazolyl, imidazolyl, oxazolidinyl, isoxazolidinyl,pyrrolyl, morpholino, piperidino, pyrrolidino, pyrazolyl, indolyl, ortetrazolyl; and R_(m) is hydrogen, (C₁ -C₁₀)alkyl, (C₃ -C₈)cycloalkyl,(C₂ -C₁₀)alkenyl, (C₂ -C₁₀)alkynyl, cyano, aryl, benzyl, phenethyl,heteroaryl, oxazolidinyl, isoxazolidinyl, or morpholinyl; wherein any(C₁ -C₁₀)alkyl, (C₃ -C₈)cycloalkyl, (C₂ -C₁₀)alkenyl, (C₂ -C₁₀)alkynyl,(C₁ -C₁₀)alkanoyl, aryl, benzyl, phenethyl, heteroaryl, arylcarbonyl,heteroarylcarbonyl, oxazolidinyl, isoxazolidinyl, or morpholinyl of R¹-R⁴, R_(a) -R_(m), or R_(p) -R_(q), may optionally be substituted with1, 2, or 3 Z; and each Z is independently halo, nitro, cyano, hydroxy,(C₁ -C₁₀)alkyl, (C₃ -C₈)cycloalkyl, (C₁ -C₁₀)alkoxy, (C₁ -C₁₀)alkanoyl,(C₂ -C₁₀)alkanoyloxy, trifluoromethyl, aryl, aryloxy, heteroaryl, or--SR_(n), wherein R_(n) is hydrogen, (C₁ -C₁₀)alkyl, (C₃ -C₈)cycloalkyl,aryl, benzyl, phenethyl, or heteroaryl; and further wherein any aryl,aryloxy, heteroaryl, benzyl, or phenethyl of Z may optionally besubstituted with 1, 2, or 3 substituents selected from the groupconsisting of halo, nitro, cyano, hydroxy, (C₁ -C₁₀)alkyl, (C₃-C₈)cycloalkyl, (C₁ -C₁₀)alkoxy, (C₁ -C₁₀)alkanoyl, (C₂-C₁₀)alkanoyloxy, benzyloxy, 4-methoxybenzyloxy, and trifluoromethyl; ora pharmaceutically acceptable salt thereof.
 2. A compound of claim 1wherein any aryl, aryloxy, heteroaryl, benzyl, or phenethyl of Z mayoptionally be substituted with 1, 2, or 3 substituents selected from thegroup consisting of halo, nitro, cyano, hydroxy, (C₁ -C₁₀)alkyl, (C₃-C₈)cycloalkyl, (C₁ -C₁₀)alkoxy, (C₁ -C₁₀)alkanoyl, (C₂-C₁₀)alkanoyloxy, and trifluoromethyl.
 3. The compound of claim 1wherein R¹ is hydrogen.
 4. The compound of claim 1 wherein R² iscarboxy, tert-butoxycarbonyl, 2-pyridyl, or methoxycarbonyl.
 5. Thecompound of claim 1 wherein R³ is --CH₂ R_(i).
 6. The compound of claim5 wherein R_(i) is halo, cyano, cyanato, --OR_(j), --NR_(k) R_(l),azido, or --SR_(m).
 7. The compound of claim 1 wherein R³ is --CH₂OR_(j).
 8. The compound of claim 7 wherein R_(j) is C₂ -alkanoyl,optionally substituted with halo, nitro, cyano, hydroxy, (C₃-C₈)cycloalkyl, (C₁ -C₁₀)alkoxy, (C₁ -C₁₀)alkanoyl, (C₂-C₁₀)alkanoyloxy, trifluoromethyl, aryl, aryloxy, heteroaryl, or--SR_(n) ; and R_(n) is hydrogen, (C₁ -C₁₀)alkyl, (C₃ -C₈)cycloalkyl,aryl, benzyl, phenethyl, or heteroaryl; wherein any aryl, aryloxy,heteroaryl, benzyl, or phenethyl may optionally be substituted with 1,2, or 3 substituents selected from the group consisting of halo, nitro,cyano, hydroxy, (C₁ -C₁₀)alkyl, (C₃ -C₈)cycloalkyl, (C₁ -C₁₀)alkoxy, (C₁-C₁₀)alkanoyl, (C₂ -C₁₀)alkanoyloxy, and trifluoromethyl.
 9. Thecompound of claim 1 wherein R³ is acetoxymethyl, phenylacetoxymethyl,phenoxyacetoxymethyl, chloroacetoxymethyl, pyridylacetoxymethyl,triazolylacetoxymethyl, imidazolylacetoxymethyl,tetrazolylthioacetoxymethyl, or tetrazolylthioacetoxymethyl optionallysubstituted on the tetrazol ring with (C₁ -C₆)alkyl, or aryl.
 10. Thecompound of claim 1 wherein R³ is acetoxymethyl, chloroacetoxymethyl,formyloxymethyl, phenylacetoxymethyl,(1-methyl-1H-tetrazol-5-ylthio)acetoxymethyl,(3,4-dihydroxyphenyl)acetoxymethyl,3,4-di(4-methoxybenzyloxy)phenylacetoxymethyl, chloromethyl, formyl, or2-cyanovinyl.
 11. The compound of claim 1 wherein R³ is acetoxymethyl,chloroacetoxymethyl, phenylacetoxymethyl,(3,4-dihydroxyphenyl)acetoxynmethyl, or(1-methyl-1H-tetrazol-5-ylthio)acetoxymethyl.
 12. The compound of claim1 wherein R⁴ is hydrogen or diphenylmethyl.
 13. The compound benzhydryl2β-(acetoxymethyl)-6-[(Z)-(t-butoxycarbonyl)-methylene]penicillinate;benzhydryl2β-(chloroacetoxymethyl)-6-[(Z)-(t-butoxycarbonyl)methylene]penicillinate;benzhydryl2β-(formyloxymethyl)-6-[(Z)-(t-butoxycarbonyl)methylene]penicillinate;benzhydryl2β-(phenylacetoxymethyl)-6-[(Z)-(t-butoxycarbonyl)methylene]penicillinate;benzhydryl2β-(acetoxymethyl)-6-[(Z)-(methoxycarbonyl)-methylene]penicillinate;benzhydryl2β-(chloroacetoxymethyl)-6-[(Z)-(-ethoxycarbonyl)methylene]penicillinate;benzhydryl2β-(acetoxymethyl)-6-[(Z)-(t-butoxycarbonyl)methylene]penicillinate-1,1-dioxide;benzhydryl2β-(chloroacetoxymethyl)-6-[(Z)-(t-butoxycarbonyl)-methylene]penicillinate1,1-dioxide; benzhydryl2β-(formyloxymethyl)-6-[(Z)-(t-butoxycarbonyl)methylene]penicillinate1,1-dioxide; benzhydryl2β-(phenylacetoxymethyl)-6-[(Z)-(t-butoxycarbonyl)-methylene]penicillinate1,1-dioxide; benzhydryl2β-(acetoxymethyl)-6-[(Z)-(methoxycarbonyl)methylene]-penicillinate1,1-dioxide; benzhydryl2β-(chloroacetoxymethyl)-6-[(Z)-(methoxycarbonyl)-methylene]penicillinate1,1-dioxide; benzhydryl2β-[[(1-methyl-1H-tetrazol-5-yl)thio]acetoxymethyl]-6-[(Z)-(t-butoxycarbonyl)-methylene]penicillinate1,1-dioxide; benzhydryl2β-[[(1-methyl-1H-tetrazol-5-yl)thio]acetoxymethyl]-6-[(Z)-(methoxycarbonyl)methylene]-penicillinate1,1-dioxide; disodium salt of2β-(acetoxymethyl)-6-[(Z)-carboxymethylene]penicillinicacid-1,1-dioxide; disodium salt of2β-(chloroacetoxymethyl)-6-[(Z)-carboxymethylene]penicillinate1,1-dioxide; disodium salt of2β-(formyloxymethyl)-6-[(Z)-carboxymethylene]-penicillinate 1,1-dioxide;disodium salt of2β-(phenylacetoxymethyl)-6-[(Z)-carboxymethylene]-penicillinate1,1-dioxide; sodium salt of2β-(acetoxymethyl)-6-[(Z)-(methoxycarbonyl)methylene]-penicillinic acid1,1 dioxide; disodium salt of2β-[[(1-methyl-f11-tetrazol-5-yl)thio]acetoxymethyl]-6-[(Z)-carboxymethylene]penicillinate1,1-dioxide; sodium salt of2β-[[(1-methyl-1H-tetrazol-5-yl)thio]acetoxymethyl]-6-[(Z)-(methoxycarbonyl)methylene]penicillinate1,1-dioxide; benzhydryl2β-(chloromethyl)-6-[(Z)-(t-butoxycarbonyl)methylene]penicillinate;benzhydryl2β-(chloromethyl)-6-[(Z)-(methoxycarbonyl)methylene]penicillinate;benzhydryl2β-(chloromethyl)-6-[(Z)-(t-butoxycarbonyl)methylene]-penicillinate1,1-dioxide; benzhydryl2p3-(chloromethyl)-6-[(Z)-(methoxycarbonyl)methylene]penicillinate1,1-dioxide; disodium salt of2β-(chloromethyl)-6-[(Z)-carboxymethylene]penicillinate 1,1-dioxide;sodium salt of2p3-(chloromethyl)-6-[(Z)-(t-butoxycarbonyl)methylene]penicillinic acid1,1 dioxide; sodium salt of2β-(chloromethyl)-6-[(Z)-(methoxycarbonyl)-methylene]penicillanic acid1,1 dioxide; benzhydryl2β-(hydroxymethyl)-6-[(Z)-(t-butoxycarbonyl)-methylene]penicillinate;benzhydryl 2β-(formyl)-6-[(Z)-(t-butoxycarbonyl)methylene]penicillinate;benzhydryl2β-[(E/Z)-(cyanoethenyl)]-6-[(Z)-(t-butoxycarbonyl)methylene]-penicillinate;benzhydryl2β-[(E/Z)-(cyanoethenyl)]-6-[(Z)-(t-butoxycarbonyl)-methylene]penicillin-ate1,1-dioxide; disodium salt of2p3-[(E/Z)-(cyanoethenyl)]-6-[(Z)-carboxymethylene]-penicillinate1,1-dioxide; benzhydryl2β-{[3',4'-Di-(p-methoxybenzyloxy)phenyl]acetoxy}-methyl-6-[(Z)-(t-butoxycarbonyl)-methylene]penicillinate;benzhydryl2β-{[3',4'-di-(p-methoxybenzyloxy)-phenyl]acetoxy}-methyl-6-[(Z)-(t-butoxycarbonyl)-methylene]-1,1-dioxopenicillinate;disodium salt of2β-[(3',4'-dihydroxyphenyl)-acetoxy]methyl-6-[(z)-carboxymethylene]-1,1-dioxopenicillinate;sodium2β-(acetoxymethyl)-1,1-dioxo-6-[(Z)-2'-pyridylmiethylene]penicillinate;or sodium1,1-dioxo-2β-(phenylacetoxy)methyl-6-[(Z)-2'-pyridylmethylene]penicillinate.14. The compound of claim 1 wherein:R¹ is hydrogen; R² is (C₁-C₁₀)alkyl, --COOR_(a), --CONR_(b) R_(c), cyano, --C(═O)Rd, --ORd, aryl,heteroaryl, oxazolidinyl, isoxazolidinyl, morpholinyl, --S(O)_(m) R_(f),--NR_(g) R_(h), azido, or halo; R³ is (C₂ -C₁₀)alkenyl, (C₂-C₁₀)alkynyl, (C₁ -C₁₀)alkanoyl, or --CH₂ R_(i), wherein R_(i) is halo,cyano, cyanato, --OR, --NR_(k) R_(l), azido, --SR_(m), or (C₃-C₈)cycloalkyl; R⁴ is hydrogen, (C₁ -C₁₀)alkyl, (C₃ -C₈)cycloalkyl, (C₂-C₁₀)alkenyl, (C₂ -C₁₀)alkynyl, aryl, or heteroaryl; m and n are eachindependently 0, 1, or 2; each R_(a) -R_(f) is independently hydrogen,(C₁ -C₁₀)alkyl, (C₃ -C₈)cycloalkyl, (C₂ -C₁₀)alkenyl, (C₂ -C₁₀)alkynyl,aryl, or heteroaryl; each R_(g) or R_(h) is independently hydrogen, (C₁-C₁₀)alkyl, (C₃ -C₈)cycloalkyl, (C₂ -C₁₀)alkenyl, (C₂ -C₁₀)alkynyl, (C₁-C₁₀)alkanoyl, aryl, benzyl, phenethyl, or or R_(g) and R_(h), togetherwith the nitrogen to which they are attached are morpholino, piperidino,or pyrrolidino; R_(j) is hydrogen, (C₁ -C₁₀)alkyl, (C₃ -C₈)cycloalkyl,(C₂ -C₁₀)alkenyl, (C₂ -C₁₀)alkynyl, --C(═O)N(R,)₂, aryl, heteroaryl,arylcarbonyl, heteroarylcarbonyl, or (C₁ -C₁₀)alkanoyl, wherein eachR_(p) is independently hydrogen, (C₁ -C₁₀)alkyl, aryl, benzyl,phenethyl, or heteroaryl; each R_(k) or R_(l) is independently hydrogen,(C₁ -C₁₀)alkyl, (C₁ -C₁₀)alkanoyl, aryl, benzyl, or phenethyl; or R_(k)and R_(l) together with the nitrogen to which they are attached aremorpholino, piperidino, or pyrrolidino; and R_(m) is hydrogen, (C₁-C₁₀)alkyl, (C₃ -C₈)cycloalkyl, (C₂ -C₁₀)alkenyl, or (C₂ -C₁₀)alkynyl;wherein any (C₁ -C₁₀)alkyl, (C₁ -C₁₀)alkanoyl, aryl, benzyl, phenethyl,heteroaryl, arylcarbonyl, or heteroarylcarbonyl of R¹ -R⁴, R_(a) -R_(m),or R_(p), may optionally be substituted with 1, 2, or 3 Z; and each Z isindependently halo, nitro, cyano, hydroxy, (C₁ -C₁₀)alkyl, (C₁-C₁₀)alkoxy, (C₁ -C₁₀)alkanoyl, (C₂ -C₁₀)alkanoyloxy, trifluoromethyl,aryl, aryloxy, heteroaryl, or --SR_(n), wherein R_(n) is hydrogen, (C₁-C₁₀)alkyl, (C₃ -C₈)cycloalkyl, aryl, benzyl, phenethyl, or heteroaryl;and further wherein any aryl, aryloxy, or heteroaryl, of Z mayoptionally be substituted with 1, 2, or 3 substituents selected from thegroup consisting of halo, nitro, cyano, hydroxy, (C₁ -C₁₀)alkyl, (C₁-C₁₀)alkoxy, (C₁ -C₁₀)alkanoyl, (C₂ -C₁₀)alkanoyloxy, andtrifluoromethyl.
 15. A pharmaceutical composition comprising a compoundof claim 1 in combination with a pharmaceutically acceptable carrier.16. A method for inhibiting a β-lactamase comprising contacting saidβ-lactamase with an effective amount of a compound of claim
 1. 17. Themethod of claim 16 wherein the β-lactamase is contacted with thecompound in vitro.
 18. The method of claim 16 wherein the β-lactamase iscontacted with the compound in vivo.
 19. A therapeutic method forinhibiting a β-lactamase in a mammal in need of such therapy, comprisingadministering an effective inhibitory amount of a compound of claim 1 tosaid mammal.
 20. The method of claim 19 wherein the mammal is a human.